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  • volume group disappeared after xfs_check run

    - by John P
    EDIT** I have a volume group consisting of 5 RAID1 devices grouped together into a lvm and formatted with xfs. The 5th RAID device lost its RAID config (cat /proc/mdstat does not show anything). The two drives are still present (sdj and sdk), but they have no partitions. The LVM appeared to be happily using sdj up until recently. (doing a pvscan showed the first 4 RAID1 devices + /dev/sdj) I removed the LVM from the fstab, rebooted, then ran xfs_check on the LV. It ran for about half an hour, then stopped with an error. I tried rebooting again, and this time when it came up, the logical volume was no longer there. It is now looking for /dev/md5, which is gone (though it had been using /dev/sdj earlier). /dev/sdj was having read errors, but after replacing the SATA cable, those went away, so the drive appears to be fine for now. Can I modify the /etc/lvm/backup/dedvol, change the device to /dev/sdj and do a vgcfgrestore? I could try doing a pvcreate --uuid KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ /dev/sdj to make it recognize it, but I'm afraid that would erase the data on the drive UPDATE: just changing the pv to point to /dev/sdj did not work vgcfgrestore --file /etc/lvm/backup/dedvol dedvol Couldn't find device with uuid 'KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ'. Cannot restore Volume Group dedvol with 1 PVs marked as missing. Restore failed. pvscan /dev/sdj: read failed after 0 of 4096 at 0: Input/output error Couldn't find device with uuid 'KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ'. Couldn't find device with uuid 'KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ'. Couldn't find device with uuid 'KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ'. Couldn't find device with uuid 'KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ'. PV /dev/sdd2 VG VolGroup00 lvm2 [74.41 GB / 0 free] PV /dev/md2 VG dedvol lvm2 [931.51 GB / 0 free] PV /dev/md3 VG dedvol lvm2 [931.51 GB / 0 free] PV /dev/md0 VG dedvol lvm2 [931.51 GB / 0 free] PV /dev/md4 VG dedvol lvm2 [931.51 GB / 0 free] PV unknown device VG dedvol lvm2 [1.82 TB / 63.05 GB free] Total: 6 [5.53 TB] / in use: 6 [5.53 TB] / in no VG: 0 [0 ] vgscan Reading all physical volumes. This may take a while... /dev/sdj: read failed after 0 of 4096 at 0: Input/output error /dev/sdj: read failed after 0 of 4096 at 2000398843904: Input/output error Found volume group "VolGroup00" using metadata type lvm2 Found volume group "dedvol" using metadata type lvm2 vgdisplay dedvol --- Volume group --- VG Name dedvol System ID Format lvm2 Metadata Areas 5 Metadata Sequence No 10 VG Access read/write VG Status resizable MAX LV 0 Cur LV 1 Open LV 0 Max PV 0 Cur PV 5 Act PV 5 VG Size 5.46 TB PE Size 4.00 MB Total PE 1430796 Alloc PE / Size 1414656 / 5.40 TB Free PE / Size 16140 / 63.05 GB VG UUID o1U6Ll-5WH8-Pv7Z-Rtc4-1qYp-oiWA-cPD246 dedvol { id = "o1U6Ll-5WH8-Pv7Z-Rtc4-1qYp-oiWA-cPD246" seqno = 10 status = ["RESIZEABLE", "READ", "WRITE"] flags = [] extent_size = 8192 # 4 Megabytes max_lv = 0 max_pv = 0 physical_volumes { pv0 { id = "Msiee7-Zovu-VSJ3-Y2hR-uBVd-6PaT-Ho9v95" device = "/dev/md2" # Hint only status = ["ALLOCATABLE"] flags = [] dev_size = 1953519872 # 931.511 Gigabytes pe_start = 384 pe_count = 238466 # 931.508 Gigabytes } pv1 { id = "ZittCN-0x6L-cOsW-v1v4-atVN-fEWF-e3lqUe" device = "/dev/md3" # Hint only status = ["ALLOCATABLE"] flags = [] dev_size = 1953519872 # 931.511 Gigabytes pe_start = 384 pe_count = 238466 # 931.508 Gigabytes } pv2 { id = "NRNo0w-kgGr-dUxA-mWnl-bU5v-Wld0-XeKVLD" device = "/dev/md0" # Hint only status = ["ALLOCATABLE"] flags = [] dev_size = 1953519872 # 931.511 Gigabytes pe_start = 384 pe_count = 238466 # 931.508 Gigabytes } pv3 { id = "2EfLFr-JcRe-MusW-mfAs-WCct-u4iV-W0pmG3" device = "/dev/md4" # Hint only status = ["ALLOCATABLE"] flags = [] dev_size = 1953519872 # 931.511 Gigabytes pe_start = 384 pe_count = 238466 # 931.508 Gigabytes } pv4 { id = "KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ" device = "/dev/md5" # Hint only status = ["ALLOCATABLE"] flags = [] dev_size = 3907028992 # 1.81935 Terabytes pe_start = 384 pe_count = 476932 # 1.81935 Terabytes } }

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  • dns server bind is not work [closed]

    - by user1742080
    I just installed bind on RHEL 6 and point a domain to that server. but actually when i ping domain it returns error 1214: Here is my named.conf: // // named.conf // // Provided by Red Hat bind package to configure the ISC BIND named(8) DNS // server as a caching only nameserver (as a localhost DNS resolver only). // // See /usr/share/doc/bind*/sample/ for example named configuration files. // options { listen-on port 53 { any; }; listen-on-v6 port 53 { ::1; }; directory "/var/named"; dump-file "/var/named/data/cache_dump.db"; statistics-file "/var/named/data/named_stats.txt"; memstatistics-file "/var/named/data/named_mem_stats.txt"; allow-query { any; }; recursion yes; dnssec-enable yes; dnssec-validation yes; dnssec-lookaside auto; /* Path to ISC DLV key */ bindkeys-file "/etc/named.iscdlv.key"; managed-keys-directory "/var/named/dynamic"; }; logging { channel default_debug { file "data/named.run"; severity dynamic; }; }; zone "." IN { type hint; file "named.ca"; }; include "/etc/named.rfc1912.zones"; include "/etc/named.root.key"; zone "mydomain.com"{ type master; file "/var/named/data/named.mydomain.com"; allow-update { none; }; }; AND The content of "/var/named/data/named.mydomain.com": 1 $TTL 38400 2 3 mydomain.com. IN SOA ns1.mydomain.com. milad.yahoo.com. ( 4 2012101201 ; serial number YYMMDDNN 5 28800 ; Refresh 6 7200 ; Retry 7 864000 ; Expire 8 38400 ; Min TTL 9 ) 10 11 mydomain.com. IN A 1.2.3.4 12 www IN A 1.2.3.4 13 ns1.mydomain.com. IN A 1.2.3.4 14 ns2.mydomain.com. IN A 1.2.3.4 15 mydomain.com. IN NS ns1.mydomain.com. 16 mydomain.com. IN NS ns2.mydomain.com. AND i'm sure the named service is running: [root@server ~]# service named status version: 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.3 CPUs found: 8 worker threads: 8 number of zones: 20 debug level: 0 xfers running: 0 xfers deferred: 0 soa queries in progress: 0 query logging is OFF recursive clients: 0/0/1000 tcp clients: 0/100 server is up and running named (pid 26299) is running...

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  • WNDR3700 Router + Cisco SG200-08 + LACP + Dual Uplink

    - by kobaltz
    Background I have a storage server that has several virtual machine images stored on them. I would store them locally, but I have limited space on my desktop (using SSD storage). I would like to increase the bandwidth between the desktop and the storage server by using two NICs on each computer. My original configuration allowed about 55MBps between the desktop and storage server. This storage server also has several TBs of documents, pictures, movies, vms, and ISO/programs. The storage server has 8 1.5TB hard drives in a RAID 10 configuration with a hardware RAID controller. The benchmarks on the RAID 10 are about 300MBps. Configuration In short, I am trying to bridge my switch and router. The switch is a small 8 port Cisco smart switch that supports 802.3ad LACP. I have two computers plugged into the switch, each with 2 Intel Gigabit NICs. The first computer is a Windows 7 machine that has the Intel ANS software installed. I have LACP configured with the computer and now show 3 NICs (2 Physical + 1 TEAM Virtual @ 2Gbps). It looks like this computer is configured correctly. I trunked the two ports that this computer is plugged into with the switch's web interface. The second computer is a homebrew storage box running debian. I also have the bonding enabled on this machine and the switch configured with LACP. Without having the WNDR3700 router in the picture yet, I am able to communicate between the Windows 7 machine and the debian box since they both have static IP addresses. With LACP enabled on both machines I am getting about 106-108MBps speeds. Issue I plug in a network cable from the switch into the router and enable DHCP on the desktop. I saw no need to have a static address on the desktop. My transfer rates are still from 106MBps-108MBps. While this is still a boost, I am trying to figure out how to get about 140-180MBps. I am thinking that I need to increase the bandwidth from the router to the switch. My switch allows 4 groups for port trunking. I plugged in a second network cable from the router to the switch. My question is, what is the proper way to fix this issue. Should I port trunk the two ports that are going from the switch to the router? Keep in mind that the router is a WNDR3700 and is unsure whether or not it supports LACP. I do have OpenWRT installed on the router, but it still wasn't clear in any documentation that I found if it supported 802.3ad LACP standards. I am also wondering if there needs to be anything changed within the Cisco settings. [Edit] - Corrected some numbers, wasn't really paying attention. It looks like the speeds though at least two NICs are bonded with LACP is still reaching the max bandwidth of one port. Is there a way to configure the switch so that I can increase this bandwidth? Also, on the storage server, I had a couple of extra NICs laying around and threw them on there as well. Another EDIT and More Findings I happened to look at the traffic of each individual NIC and think that I see the problem. I tested with a simple transfer for a 4GB file. I noticed that only one of the NICs was taking the load of the traffic. I then copied the file back to the Storage Server and noticed that the other NIC was sending out the traffic. I have 802.3ad LACP enabled on the two NICs and I see that it gets enabled dynamically on the switch's interface. Should I be using Static Link Aggregation?

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  • "ID 046d:c50e Logitech, Inc. Cordless Mouse Receiver" wheel-click is wrong

    - by sputnick
    I use this mouse under archlinux x86_64 with 3.2.8-1-ARCH kernel. I have some problems to select and then paste with the wheel-click in some applications like konversation, not in a terminal nor an editor. I don't know if it's a hardware problem or a software one. $ lsusb -v Bus 002 Device 110: ID 046d:c50e Logitech, Inc. Cordless Mouse Receiver Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 1.10 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 8 idVendor 0x046d Logitech, Inc. idProduct 0xc50e Cordless Mouse Receiver bcdDevice 25.10 iManufacturer 1 Logitech iProduct 2 USB RECEIVER iSerial 0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 34 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xa0 (Bus Powered) Remote Wakeup MaxPower 70mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 3 Human Interface Device bInterfaceSubClass 1 Boot Interface Subclass bInterfaceProtocol 2 Mouse iInterface 0 HID Device Descriptor: bLength 9 bDescriptorType 33 bcdHID 1.11 bCountryCode 0 Not supported bNumDescriptors 1 bDescriptorType 34 Report wDescriptorLength 95 Report Descriptors: ** UNAVAILABLE ** Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0008 1x 8 bytes bInterval 10 Device Status: 0x0000 (Bus Powered) When I see what's happens in xev, the output is different compared to another mouse My buggy Logitech mouse : ButtonPress event, serial 40, synthetic NO, window 0x4400001, root 0x15a, subw 0x4400002, time 170350700, (48,52), root:(1491,75), state 0x10, button 11, same_screen YES EnterNotify event, serial 40, synthetic NO, window 0x4400001, root 0x15a, subw 0x0, time 170350700, (48,52), root:(1491,75), mode NotifyGrab, detail NotifyInferior, same_screen YES, focus YES, state 16 KeymapNotify event, serial 40, synthetic NO, window 0x0, keys: 90 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ButtonPress event, serial 40, synthetic NO, window 0x4400001, root 0x15a, subw 0x4400002, time 170350716, (48,52), root:(1491,75), state 0x10, button 6, same_screen YES ButtonRelease event, serial 40, synthetic NO, window 0x4400001, root 0x15a, subw 0x4400002, time 170350716, (48,52), root:(1491,75), state 0x10, button 6, same_screen YES ButtonRelease event, serial 40, synthetic NO, window 0x4400001, root 0x15a, subw 0x4400002, time 170350988, (48,52), root:(1491,75), state 0x10, button 11, same_screen YES LeaveNotify event, serial 40, synthetic NO, window 0x4400001, root 0x15a, subw 0x0, time 170350988, (48,52), root:(1491,75), mode NotifyUngrab, detail NotifyInferior, same_screen YES, focus YES, state 16 a working mouse (dell) : ButtonPress event, serial 40, synthetic NO, window 0x4400001, root 0x15a, subw 0x4400002, time 170245131, (46,32), root:(1489,55), state 0x10, button 2, same_screen YES EnterNotify event, serial 40, synthetic NO, window 0x4400001, root 0x15a, subw 0x0, time 170245131, (46,32), root:(1489,55), mode NotifyGrab, detail NotifyInferior, same_screen YES, focus YES, state 528 KeymapNotify event, serial 40, synthetic NO, window 0x0, keys: 90 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ButtonRelease event, serial 40, synthetic NO, window 0x4400001, root 0x15a, subw 0x4400002, time 170245411, (46,32), root:(1489,55), state 0x210, button 2, same_screen YES LeaveNotify event, serial 40, synthetic NO, window 0x4400001, root 0x15a, subw 0x0, time 170245411, (46,32), root:(1489,55), mode NotifyUngrab, detail NotifyInferior, same_screen YES, focus YES, state 16 A demo of the problem when I use konversation (IRC) : http://www.youtube.com/watch?v=lhmr92M7NCc I tried to modify the button map with xmodmap like this with no success (one at a time) : xmodmap -e "pointer = 1 0 3" xmodmap -e "pointer = 1 1 3" xmodmap -e "pointer = 1 2 3" xmodmap -e "pointer = 1 3 3" xmodmap -e "pointer = 1 4 3" xmodmap -e "pointer = 1 5 3" xmodmap -e "pointer = 1 6 3" xmodmap -e "pointer = 1 7 3" xmodmap -e "pointer = 1 8 3" xmodmap -e "pointer = 1 9 3" xmodmap -e "pointer = 1 10 3" xmodmap -e "pointer = 1 11 3" xmodmap -e "pointer = 1 12 3" xmodmap -e "pointer = 1 13 3" xmodmap -e "pointer = 1 14 3" xmodmap -e "pointer = 1 15 3" xmodmap -e "pointer = 1 16 3" xmodmap -e "pointer = 1 17 3" xmodmap -e "pointer = 1 18 3" xmodmap -e "pointer = 1 19 3" xmodmap -e "pointer = 1 20 3" xmodmap -e "pointer = 1 21 3" xmodmap -e "pointer = 1 22 3" xmodmap -e "pointer = 1 23 3" xmodmap -e "pointer = 1 24 3" xmodmap -e "pointer = 1 25 3" Any clue ? I would like to avoid buying a new mouse just for a paste problem.

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  • RedHat 5.5 server does not show per processor memory utilization

    - by Mike S
    I have been searching all over internet but not finding any leads. I have a system with a memory leak that I am trying to troubleshoot. Unfortunately I am not able to see per processor memory utilization. Here are the outputs of TOP and PS commands. Linux SERVER_NAME 2.6.18-194.8.1.el5 #1 SMP Wed Jun 23 10:52:51 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux top - 09:17:13 up 18:43, 3 users, load average: 0.00, 0.00, 0.00 Tasks: 375 total, 1 running, 373 sleeping, 0 stopped, 1 zombie Cpu(s): 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 32922828k total, 32776712k used, 146116k free, 267128k buffers Swap: 5245212k total, 0k used, 5245212k free, 32141044k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1 root 15 0 10348 744 620 S 0.0 0.0 0:05.65 init 2 root RT -5 0 0 0 S 0.0 0.0 0:00.05 migration/0 3 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/0 4 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/0 5 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/1 6 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/1 7 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/1 8 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/2 9 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/2 10 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/2 11 root RT -5 0 0 0 S 0.0 0.0 0:00.01 migration/3 12 root 34 19 0 0 0 S 0.0 0.0 0:00.01 ksoftirqd/3 13 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/3 14 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/4 15 root 34 19 0 0 0 S 0.0 0.0 0:00.01 ksoftirqd/4 16 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/4 17 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/5 18 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/5 19 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/5 20 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/6 % ps -auxf | sort -nr -k 4 | head -10 Warning: bad syntax, perhaps a bogus '-'? See /usr/share/doc/procps-3.2.7/FAQ xfs 6205 0.0 0.0 23316 3892 ? Ss Aug19 0:00 xfs -droppriv -daemon uuidd 6101 0.0 0.0 60976 224 ? Ss Aug19 0:00 /usr/sbin/uuidd USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND smmsp 6130 0.0 0.0 57900 1784 ? Ss Aug19 0:00 sendmail: Queue runner@01:00:00 for /var/spool/clientmqueue rpc 5126 0.0 0.0 8052 632 ? Ss Aug19 0:00 portmap root 99 0.0 0.0 0 0 ? S< Aug19 0:00 [events/1] root 98 0.0 0.0 0 0 ? S< Aug19 0:00 [events/0] root 97 0.0 0.0 0 0 ? S< Aug19 0:00 [watchdog/31] root 96 0.0 0.0 0 0 ? SN Aug19 0:00 [ksoftirqd/31] root 95 0.0 0.0 0 0 ? S< Aug19 0:00 [migration/31] Any help with this is appretiate.

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  • Optimise Apache for EC2 micro instance

    - by Shiyu Sekam
    I'm running apache2 on a EC2 micro instance with ~600 mb RAM. The instance was running for almost a year without problems, but in the last weeks it just keeps crashing, because the server reached MaxClients. The server basically runs few websites, one wordpress blog(not often used), company website(most used) and 2 small sites, which are just internal. The database for the blog runs on RDS, so there's no Mysql running on this web server. When I came to the company, the server already was setup and is running apache + mod_php + prefork. We want to migrate that in the future to a nginx + php-fpm, but it still needs further testing. So for now I have to stick with the old setup. I also use CloudFlare DDOS protection in front of the server, because it was attacked a couple of the times in the last weeks. My company don't want to pay money for a better web server at this point, so I have to stick with the micro instance also. Additionally the code for the website we run is really bad and slow and sometimes a single page load can take up to 15 seconds. The whole website is dynamic and written in PHP, so caching isn't really an option here. It's a customized search for users. I've already turned off KeepAlive, which improved the performance a little bit. My prefork config looks like the following: StartServers 2 MinSpareServers 2 MaxSpareServers 5 ServerLimit 10 MaxClients 10 MaxRequestsPerChild 100 The server just becomes unresponsive after a while running and I've run the following command to see how many connections there are: netstat | grep http | wc -l 75 Trying to restart apache helps for a short moment, but after that a while the apache process(es) become unresponsive again. I've the following modules enabled(output of apache2ctl -M) Loaded Modules: core_module (static) log_config_module (static) logio_module (static) version_module (static) mpm_prefork_module (static) http_module (static) so_module (static) alias_module (shared) authz_host_module (shared) deflate_module (shared) dir_module (shared) expires_module (shared) mime_module (shared) negotiation_module (shared) php5_module (shared) rewrite_module (shared) setenvif_module (shared) ssl_module (shared) status_module (shared) Syntax OK apache2.conf # Security ServerTokens OS ServerSignature On TraceEnable On ServerName "web.example.com" ServerRoot "/etc/apache2" PidFile ${APACHE_PID_FILE} Timeout 30 KeepAlive off User www-data Group www-data AccessFileName .htaccess <Files ~ "^\.ht"> Order allow,deny Deny from all Satisfy all </Files> <Directory /> Options FollowSymLinks AllowOverride None </Directory> DefaultType none HostnameLookups Off ErrorLog /var/log/apache2/error.log LogLevel warn EnableSendfile On #Listen 80 Include /etc/apache2/mods-enabled/*.load Include /etc/apache2/mods-enabled/*.conf Include /etc/apache2/ports.conf LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined LogFormat "%h %l %u %t \"%r\" %>s %b" common LogFormat "%{Referer}i -> %U" referer LogFormat "%{User-agent}i" agent Include /etc/apache2/conf.d/*.conf Include /etc/apache2/sites-enabled/*.conf Vhost of main site <VirtualHost *:80> ServerName www.example.com ## Vhost docroot DocumentRoot /srv/www/jenkins/Web ## Directories, there should at least be a declaration for /srv/www/jenkins/Web <Directory /srv/www/jenkins/Web> AllowOverride All Order allow,deny Allow from all </Directory> ## Load additional static includes ## Logging ErrorLog /var/log/apache2/www.example.com.error.log LogLevel warn ServerSignature Off CustomLog /var/log/apache2/www.example.com.access.log combined ## Rewrite rules RewriteEngine On RewriteCond %{HTTP_HOST} !^www.example.com$ RewriteRule ^.*$ http://www.example.com%{REQUEST_URI} [R=301,L] ## Server aliases ServerAlias www.example.invalid ServerAlias example.com ## Custom fragment <Location /srv/www/jenkins/Web/library> Order Deny,Allow Deny from all </Location> <Files ~ "^\.(.+)"> Order deny,allow deny from all </Files> </VirtualHost>

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  • How do bots access directories on a server that are not DocumentRoot of public IP address? How do I stop them?

    - by tmsimont
    I have a local network set up with apache2 and "named" running on OpenSuse 13.1 Linux. I used the "named" service to use my computer as a domain server. I set up my router to point to ask my computer for domain lookups, so I have a chance to have it rewrite a bunch of domains on my network to its own local IP, 192.168.0.111 This works great. I use virtual host configuration to allow various domains and subdomains (re-routed to the same IP via named) to pull up different directories in my computer. For example: <VirtualHost *:80> ServerName 192.168.0.111 ServerAlias fmb.wa.net DocumentRoot /home/work/wa.net/fmb </VirtualHost> <VirtualHost *:80> ServerName 192.168.0.111 ServerAlias postrecord.wa.net DocumentRoot /home/work/wa.net/postrecord </VirtualHost> <VirtualHost *:80> ServerName 192.168.0.111 ServerAlias cvalley.wa.net DocumentRoot /home/work/wa.net/cvalley_local </VirtualHost> This makes it possible for me to hit cvalley.wa.net from any device in my network and get the site that lives in /home/work/wa.net/cvalley_local I decided to forward port 80 to this computer, so I could share a few development sites with coworkers. I can't control which site they see with the same named service, because they'd have to use my computer as their domain name server... So I added a line like this: <VirtualHost *:80> ServerName 192.168.0.111 ServerAlias MY.IP.XXX.XX DocumentRoot /home/work/wa.net/cvalley </VirtualHost> Where "MY.IP.XXX.XX" is my public IP address. This works as expected, when you hit my IP address from a public network you see the site that lives in /home/work/wa.net/cvalley. The point of confusion that I have is that there are public IP addresses in my logs in other sites. I would have expected it to be impossible to access other sites in my network, unless the public user somehow figured out what I'm calling my ServerAliases, and is mimicing my domain set up... How can public traffic be hitting my other local sites? How can I recreate this kind of access? Here are some examples of public IP's hitting my VirtualHost sites: 162.253.66.76 - - [15/Aug/2014:19:20:47 -0600] "GET /xmlrpc.php HTTP/1.0" 404 1004 "-" "-" 162.253.66.74 - - [16/Aug/2014:10:50:28 -0600] "GET / HTTP/1.0" 200 262 "-" "masscan/1.0 (https://github.com/robertdavidgraham/masscan)" 185.4.227.194 - - [16/Aug/2014:11:16:45 -0600] "GET http://24x7-allrequestsallowed.com/?PHPSESSID=1rysxtj500143WQMVT%5E_NAZ%5BQ HTTP/1.1" 200 262 "-" "-" 101.226.254.138 - - [16/Aug/2014:13:32:14 -0600] "HEAD / HTTP/1.0" 200 - "-" "-" 162.253.66.74 - - [16/Aug/2014:14:26:19 -0600] "GET / HTTP/1.0" 200 262 "-" "masscan/1.0 (https://github.com/robertdavidgraham/masscan)" 212.129.2.119 - - [16/Aug/2014:16:00:51 -0600] "HEAD / HTTP/1.0" 200 - "-" "-" 91.240.163.111 - - [16/Aug/2014:18:34:32 -0600] "GET / HTTP/1.0" 200 262 "-" "masscan/1.0 (https://github.com/robertdavidgraham/masscan)" 162.253.66.74 - - [16/Aug/2014:19:02:53 -0600] "GET / HTTP/1.0" 200 262 "-" "masscan/1.0 (https://github.com/robertdavidgraham/masscan)" 122.226.223.69 - - [17/Aug/2014:05:53:09 -0600] "GET http://www.k2proxy.com//hello.html HTTP/1.1" 404 1006 "-" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/6.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E)" ::1 - - [17/Aug/2014:10:19:26 -0600] "OPTIONS * HTTP/1.0" 200 - "-" "Apache/2.4.6 (Linux/SUSE) OpenSSL/1.0.1e PHP/5.4.20 (internal dummy connection)" 162.209.65.196 - - [17/Aug/2014:15:31:53 -0600] "HEAD / HTTP/1.0" 200 - "-" "-" 111.206.199.163 - - [18/Aug/2014:11:12:56 -0600] "HEAD / HTTP/1.0" 200 - "-" "-" 37.187.180.168 - - [18/Aug/2014:15:40:00 -0600] "HEAD / HTTP/1.0" 200 - "-" "-" 62.210.38.226 - - [18/Aug/2014:18:35:16 -0600] "HEAD / HTTP/1.0" 200 - "-" "-" Is there anything that I can do to reliably deny public access by default, but allow it only in one VirtualHost?

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  • how to install 'version.h' in ubuntu ?

    - by user252098
    Just now , I try to install the Jungo WinDriver in the Ubuntu 13.10 . But I am puzzled by the its manual of how to Install version.h : Install version.h: The file version.h is created when you first compile the Linux kernel source code. Some distributions provide a compiled kernel without the file version.h. Look under /usr/src/linux/include/linux to see whether you have this file. If you do not, follow these steps: Become super user: $ su Change directory to the Linux source directory: # cd /usr/src/linux Type: # make xconfig Save the configuration by choosing Save and Exit. Type: # make dep Exit super user mode: # exit But the shell says: warning: make dep is unnecessary now. Then, I found out there is a version.h in /usr/src/linux-headers-3.11.0.12-generic, so I type: /usr/src/windriver/redist# ./configure --with-kernel-source=/usr/src/linux-headers-3.11.0.12-generic But, the windriver run fails: USE_KBUILD = yes checking for cpu architecture... x86_64 checking for WinDriver root directory... /usr/src/WinDriver checking for linux kernel source... found at /usr/src/linux checking for lib directory... ln -sf $(ROOT_DIR)/lib/$(SHARED_OBJECT)_32.so /usr/lib/$(SHARED_OBJECT).so; ln -s /usr/lib /usr/lib64; ln -sf $(ROOT_DIR)/lib/$(SHARED_OBJECT).so /usr/lib64/$(SHARED_OBJECT).so checking which directories to include... -I/usr/src/linux/include checking linux kernel version... 3.11.10.6 checking for modules installation directory... /lib/modules/3.11.0-12-generic/kernel/drivers/misc checking output directory... LINUX.3.11.0-12-generic.x86_64 checking target... LINUX.3.11.0-12-generic.x86_64/windrvr6_usb.ko checking for regparm kernel option... find: `/usr/src/WinDriver/redist/.tmp_driver/.tmp_versions': No such file or directory 0 checking for modpost location... /usr/src/linux/scripts/mod/modpost configure.usb: creating ./config.status config.status: creating makefile.usb.kbuild checking for cpu architecture... x86_64 checking for WinDriver root directory... /usr/src/WinDriver checking for linux kernel source... found at /usr/src/linux checking for lib directory... ln -sf $(ROOT_DIR)/lib/$(SHARED_OBJECT)_32.so /usr/lib/$(SHARED_OBJECT).so; ln -s /usr/lib /usr/lib64; ln -sf $(ROOT_DIR)/lib/$(SHARED_OBJECT).so /usr/lib64/$(SHARED_OBJECT).so checking which directories to include... -I/usr/src/linux/include checking linux kernel version... 3.11.10.6 checking for modules installation directory... /lib/modules/3.11.0-12-generic/kernel/drivers/misc checking output directory... LINUX.3.11.0-12-generic.x86_64 checking target... LINUX.3.11.0-12-generic.x86_64/windrvr6.ko checking for regparm kernel option... find: `/usr/src/WinDriver/redist/.tmp_driver/.tmp_versions': No such file or directory 0 checking for right linked object... windrvr_gcc_v3.a checking for modpost location... /usr/src/linux/scripts/mod/modpost configure.wd: creating ./config.status config.status: creating makefile.wd.kbuild What is the problem?

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  • Week in Geek: US Govt E-card Scam Siphons Confidential Data Edition

    - by Asian Angel
    This week we learned how to “back up photos to Flickr, automate repetitive tasks, & normalize MP3 volume”, enable “stereo mix” in Windows 7 to record audio, create custom papercraft toys, read up on three alternatives to Apple’s flaky iOS alarm clock, decorated our desktops & app docks with Google icon packs, and more. Photo by alexschlegel. Random Geek Links It has been a busy week on the security & malware fronts and we have a roundup of the latest news to help keep you updated. Photo by TopTechWriter.US. US govt e-card scam hits confidential data A fake U.S. government Christmas e-card has managed to siphon off gigabytes of sensitive data from a number of law enforcement and military staff who work on cybersecurity matters, many of whom are involved in computer crime investigations. Security tool uncovers multiple bugs in every browser Michal Zalewski reports that he discovered the vulnerability in Internet Explorer a while ago using his cross_fuzz fuzzing tool and reported it to Microsoft in July 2010. Zalewski also used cross_fuzz to discover bugs in other browsers, which he also reported to the relevant organisations. Microsoft to fix Windows holes, but not ones in IE Microsoft said that it will release two security bulletins next week fixing three holes in Windows, but it is still investigating or working on fixing holes in Internet Explorer that have been reportedly exploited in attacks. Microsoft warns of Windows flaw affecting image rendering Microsoft has warned of a Windows vulnerability that could allow an attacker to take control of a computer if the user is logged on with administrative rights. Windows 7 Not Affected by Critical 0-Day in the Windows Graphics Rendering Engine While confirming that details on a Critical zero-day vulnerability have made their way into the wild, Microsoft noted that customers running the latest iteration of Windows client and server platforms are not exposed to any risks. Microsoft warns of Office-related malware Microsoft’s Malware Protection Center issued a warning this week that it has spotted malicious code on the Internet that can take advantage of a flaw in Word and infect computers after a user does nothing more than read an e-mail. *Refers to a flaw that was addressed in the November security patch releases. Make sure you have all of the latest security updates installed. Unpatched hole in ImgBurn disk burning application According to security specialist Secunia, a highly critical vulnerability in ImgBurn, a lightweight disk burning application, can be used to remotely compromise a user’s system. Hole in VLC Media Player Virtual Security Research (VSR) has identified a vulnerability in VLC Media Player. In versions up to and including 1.1.5 of the VLC Media Player. Flash Player sandbox can be bypassed Flash applications run locally can read local files and send them to an online server – something which the sandbox is supposed to prevent. Chinese auction site touts hacked iTunes accounts Tens of thousands of reportedly hacked iTunes accounts have been found on Chinese auction site Taobao, but the company claims it is unable to take action unless there are direct complaints. What happened in the recent Hotmail outage Mike Schackwitz explains the cause of the recent Hotmail outage. DOJ sends order to Twitter for Wikileaks-related account info The U.S. Justice Department has obtained a court order directing Twitter to turn over information about the accounts of activists with ties to Wikileaks, including an Icelandic politician, a legendary Dutch hacker, and a U.S. computer programmer. Google gets court to block Microsoft Interior Department e-mail win The U.S. Federal Claims Court has temporarily blocked Microsoft from proceeding with the $49.3 million, five-year DOI contract that it won this past November. Google Apps customers get email lockdown Companies and organisations using Google Apps are now able to restrict the email access of selected users. LibreOffice Is the Default Office Suite for Ubuntu 11.04 Matthias Klose has announced some details regarding the replacement of the old OpenOffice.org 3.2.1 packages with the new LibreOffice 3.3 ones, starting with the upcoming Ubuntu 11.04 (Natty Narwhal) Alpha 2 release. Sysadmin Geek Tips Photo by Filomena Scalise. How to Setup Software RAID for a Simple File Server on Ubuntu Do you need a file server that is cheap and easy to setup, “rock solid” reliable, and has Email Alerting? This tutorial shows you how to use Ubuntu, software RAID, and SaMBa to accomplish just that. How to Control the Order of Startup Programs in Windows While you can specify the applications you want to launch when Windows starts, the ability to control the order in which they start is not available. However, there are a couple of ways you can easily overcome this limitation and control the startup order of applications. Random TinyHacker Links Using Opera Unite to Send Large Files A tutorial on using Opera Unite to easily send huge files from your computer. WorkFlowy is a Useful To-do List Tool A cool to-do list tool that lets you integrate multiple tasks in one single list easily. Playing Flash Videos on iOS Devices Yes, you can play flash videos on jailbroken iPhones. Here’s a tutorial. Clear Safari History and Cookies On iPhone A tutorial on clearing your browser history on iPhone and other iOS devices. Monitor Your Internet Usage Here’s a cool, cross-platform tool to monitor your internet bandwidth. Super User Questions See what the community had to say on these popular questions from Super User this week. Why is my upload speed much less than my download speed? Where should I find drivers for my laptop if it didn’t come with a driver disk? OEM Office 2010 without media – how to reinstall? Is there a point to using theft tracking software like Prey on my laptop, if you have login security? Moving an “all-in-one” PC when turned on/off How-To Geek Weekly Article Recap Get caught up on your HTG reading with our hottest articles from this past week. How to Combine Rescue Disks to Create the Ultimate Windows Repair Disk How To Boot 10 Different Live CDs From 1 USB Flash Drive What is Camera Raw, and Why Would a Professional Prefer it to JPG? Did You Know Facebook Has Built-In Shortcut Keys? The How-To Geek Guide to Audio Editing: The Basics One Year Ago on How-To Geek Enjoy looking through our latest gathering of retro article goodness. Learning Windows 7: Create a Homegroup & Join a New Computer To It How To Disconnect a Machine from a Homegroup Use Remote Desktop To Access Other Computers On a Small Office or Home Network How To Share Files and Printers Between Windows 7 and Vista Allow Users To Run Only Specified Programs in Windows 7 The Geek Note That is all we have for you this week and we hope your first week back at work or school has gone very well now that the holidays are over. Know a great tip? Send it in to us at [email protected]. Photo by Pamela Machado. Latest Features How-To Geek ETC HTG Projects: How to Create Your Own Custom Papercraft Toy How to Combine Rescue Disks to Create the Ultimate Windows Repair Disk What is Camera Raw, and Why Would a Professional Prefer it to JPG? The How-To Geek Guide to Audio Editing: The Basics How To Boot 10 Different Live CDs From 1 USB Flash Drive The 20 Best How-To Geek Linux Articles of 2010 Arctic Theme for Windows 7 Gives Your Desktop an Icy Touch Install LibreOffice via PPA and Receive Auto-Updates in Ubuntu Creative Portraits Peek Inside the Guts of Modern Electronics Scenic Winter Lane Wallpaper to Create a Relaxing Mood Access Your Web Apps Directly Using the Context Menu in Chrome The Deep – Awesome Use of Metal Objects as Deep Sea Creatures [Video]

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  • Why do I have to run aptitude update twice to install Ruby?

    - by Willie Wheeler
    Summary. I have a fresh EC2 Precise 64-bit instance (ami-82fa58eb). After launching the instance, I want to install ruby1.9.1 (among others). This doesn't work: aptitude update && apt-get -o Dpkg::Options::="--force-confnew" --force-yes -fuy dist-upgrade && aptitude install -y ruby1.9.1 ruby1.9.1-dev make as Aptitude can't find the Ruby package. But this works: aptitude update && aptitude update && apt-get -o Dpkg::Options::="--force-confnew" --force-yes -fuy dist-upgrade && aptitude install -y ruby1.9.1 ruby1.9.1-dev make I would like to understand why I need to run aptitude update twice. Details. The first and second runs look pretty different. First run: Ign http://security.ubuntu.com precise-security InRelease Ign http://archive.ubuntu.com precise InRelease Get: 1 http://security.ubuntu.com precise-security Release.gpg [198 B] Ign http://archive.ubuntu.com precise-updates InRelease Get: 2 http://security.ubuntu.com precise-security Release [49.6 kB] Hit http://archive.ubuntu.com precise Release.gpg Get: 3 http://archive.ubuntu.com precise-updates Release.gpg [198 B] Hit http://archive.ubuntu.com precise Release Get: 4 http://security.ubuntu.com precise-security/main amd64 Packages [161 kB] Get: 5 http://archive.ubuntu.com precise-updates Release [49.6 kB] Get: 6 http://security.ubuntu.com precise-security/restricted amd64 Packages [3,969 B] Hit http://archive.ubuntu.com precise/main amd64 Packages Get: 7 http://security.ubuntu.com precise-security/universe amd64 Packages [43.8 kB] Hit http://archive.ubuntu.com precise/restricted amd64 Packages Hit http://archive.ubuntu.com precise/universe amd64 Packages Get: 8 http://security.ubuntu.com precise-security/multiverse amd64 Packages [2,180 B] Hit http://archive.ubuntu.com precise/multiverse amd64 Packages Get: 9 http://security.ubuntu.com precise-security/main i386 Packages [165 kB] Hit http://archive.ubuntu.com precise/main i386 Packages Hit http://archive.ubuntu.com precise/restricted i386 Packages Hit http://archive.ubuntu.com precise/universe i386 Packages Hit http://archive.ubuntu.com precise/multiverse i386 Packages Get: 10 http://security.ubuntu.com precise-security/restricted i386 Packages [3,968 B] Hit http://archive.ubuntu.com precise/main TranslationIndex Get: 11 http://security.ubuntu.com precise-security/universe i386 Packages [44.0 kB] Hit http://archive.ubuntu.com precise/multiverse TranslationIndex Get: 12 http://security.ubuntu.com precise-security/multiverse i386 Packages [2,369 B] Get: 13 http://security.ubuntu.com precise-security/main TranslationIndex [73 B] Hit http://archive.ubuntu.com precise/restricted TranslationIndex Get: 14 http://security.ubuntu.com precise-security/multiverse TranslationIndex [71 B] Hit http://archive.ubuntu.com precise/universe TranslationIndex Get: 15 http://security.ubuntu.com precise-security/restricted TranslationIndex [71 B] Get: 16 http://archive.ubuntu.com precise-updates/main amd64 Packages [382 kB] Get: 17 http://security.ubuntu.com precise-security/universe TranslationIndex [73 B] Get: 18 http://security.ubuntu.com precise-security/main Translation-en [76.5 kB] Get: 19 http://security.ubuntu.com precise-security/multiverse Translation-en [995 B] Get: 20 http://security.ubuntu.com precise-security/restricted Translation-en [978 B] Get: 21 http://security.ubuntu.com precise-security/universe Translation-en [27.2 kB] Get: 22 http://archive.ubuntu.com precise-updates/restricted amd64 Packages [6,755 B] Get: 23 http://archive.ubuntu.com precise-updates/universe amd64 Packages [129 kB] Get: 24 http://archive.ubuntu.com precise-updates/multiverse amd64 Packages [8,677 B] Get: 25 http://archive.ubuntu.com precise-updates/main i386 Packages [387 kB] Get: 26 http://archive.ubuntu.com precise-updates/restricted i386 Packages [6,732 B] Get: 27 http://archive.ubuntu.com precise-updates/universe i386 Packages [130 kB] Get: 28 http://archive.ubuntu.com precise-updates/multiverse i386 Packages [9,672 B] Get: 29 http://archive.ubuntu.com precise-updates/main TranslationIndex [3,564 B] Get: 30 http://archive.ubuntu.com precise-updates/multiverse TranslationIndex [2,605 B] Get: 31 http://archive.ubuntu.com precise-updates/restricted TranslationIndex [2,461 B] Get: 32 http://archive.ubuntu.com precise-updates/universe TranslationIndex [2,850 B] Get: 33 http://archive.ubuntu.com precise/main Translation-en [726 kB] Get: 34 http://archive.ubuntu.com precise/multiverse Translation-en [93.4 kB] Get: 35 http://archive.ubuntu.com precise/restricted Translation-en [2,395 B] Get: 36 http://archive.ubuntu.com precise/universe Translation-en [3,341 kB] Get: 37 http://archive.ubuntu.com precise-updates/main Translation-en [188 kB] Get: 38 http://archive.ubuntu.com precise-updates/multiverse Translation-en [5,414 B] Get: 39 http://archive.ubuntu.com precise-updates/restricted Translation-en [1,484 B] Get: 40 http://archive.ubuntu.com precise-updates/universe Translation-en [77.3 kB] Ign http://archive.ubuntu.com precise/main Translation-en_US Ign http://archive.ubuntu.com precise/multiverse Translation-en_US Ign http://archive.ubuntu.com precise/restricted Translation-en_US Ign http://archive.ubuntu.com precise/universe Translation-en_US Fetched 6,137 kB in 11s (538 kB/s) Reading package lists... Second run: Ign http://us-east-1.ec2.archive.ubuntu.com precise InRelease Ign http://us-east-1.ec2.archive.ubuntu.com precise-updates InRelease Get: 1 http://us-east-1.ec2.archive.ubuntu.com precise Release.gpg [198 B] Get: 2 http://us-east-1.ec2.archive.ubuntu.com precise-updates Release.gpg [198 B] Ign http://security.ubuntu.com precise-security InRelease Get: 3 http://us-east-1.ec2.archive.ubuntu.com precise Release [49.6 kB] Get: 4 http://us-east-1.ec2.archive.ubuntu.com precise-updates Release [49.6 kB] Get: 5 http://us-east-1.ec2.archive.ubuntu.com precise/main Sources [934 kB] Hit http://security.ubuntu.com precise-security Release.gpg Hit http://security.ubuntu.com precise-security Release Get: 6 http://us-east-1.ec2.archive.ubuntu.com precise/universe Sources [5,019 kB] Get: 7 http://security.ubuntu.com precise-security/main Sources [42.8 kB] Get: 8 http://security.ubuntu.com precise-security/universe Sources [13.5 kB] Hit http://security.ubuntu.com precise-security/main amd64 Packages Hit http://security.ubuntu.com precise-security/universe amd64 Packages Hit http://security.ubuntu.com precise-security/main i386 Packages Get: 9 http://us-east-1.ec2.archive.ubuntu.com precise/main amd64 Packages [1,273 kB] Hit http://security.ubuntu.com precise-security/universe i386 Packages Get: 10 http://us-east-1.ec2.archive.ubuntu.com precise/universe amd64 Packages [4,786 kB] Hit http://security.ubuntu.com precise-security/main TranslationIndex Hit http://security.ubuntu.com precise-security/universe TranslationIndex Hit http://security.ubuntu.com precise-security/main Translation-en Hit http://security.ubuntu.com precise-security/universe Translation-en Get: 11 http://us-east-1.ec2.archive.ubuntu.com precise/main i386 Packages [1,274 kB] Get: 12 http://us-east-1.ec2.archive.ubuntu.com precise/universe i386 Packages [4,796 kB] Get: 13 http://us-east-1.ec2.archive.ubuntu.com precise/main TranslationIndex [3,706 B] Get: 14 http://us-east-1.ec2.archive.ubuntu.com precise/universe TranslationIndex [2,922 B] Get: 15 http://us-east-1.ec2.archive.ubuntu.com precise-updates/main Sources [163 kB] Get: 16 http://us-east-1.ec2.archive.ubuntu.com precise-updates/universe Sources [50.8 kB] Get: 17 http://us-east-1.ec2.archive.ubuntu.com precise-updates/main amd64 Packages [382 kB] Get: 18 http://us-east-1.ec2.archive.ubuntu.com precise-updates/universe amd64 Packages [129 kB] Get: 19 http://us-east-1.ec2.archive.ubuntu.com precise-updates/main i386 Packages [387 kB] Get: 20 http://us-east-1.ec2.archive.ubuntu.com precise-updates/universe i386 Packages [129 kB] Get: 21 http://us-east-1.ec2.archive.ubuntu.com precise-updates/main TranslationIndex [3,564 B] Get: 22 http://us-east-1.ec2.archive.ubuntu.com precise-updates/universe TranslationIndex [2,850 B] Get: 23 http://us-east-1.ec2.archive.ubuntu.com precise/main Translation-en [726 kB] Get: 24 http://us-east-1.ec2.archive.ubuntu.com precise/universe Translation-en [3,341 kB] Get: 25 http://us-east-1.ec2.archive.ubuntu.com precise-updates/main Translation-en [188 kB] Get: 26 http://us-east-1.ec2.archive.ubuntu.com precise-updates/universe Translation-en [77.1 kB] Fetched 23.8 MB in 23s (1,026 kB/s) Reading package lists... Note. My question is almost exactly the same as Running 'apt-get upgrade' on Amazon EC2 AMI twice in succession upgrades very different packages except that I'm seeing this issue with aptitude updates rather than apt-get upgrades.

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  • Introducing Oracle VM Server for SPARC

    - by Honglin Su
    As you are watching Oracle's Virtualization Strategy Webcast and exploring the great virtualization offerings of Oracle VM product line, I'd like to introduce Oracle VM Server for SPARC --  highly efficient, enterprise-class virtualization solution for Sun SPARC Enterprise Systems with Chip Multithreading (CMT) technology. Oracle VM Server for SPARC, previously called Sun Logical Domains, leverages the built-in SPARC hypervisor to subdivide supported platforms' resources (CPUs, memory, network, and storage) by creating partitions called logical (or virtual) domains. Each logical domain can run an independent operating system. Oracle VM Server for SPARC provides the flexibility to deploy multiple Oracle Solaris operating systems simultaneously on a single platform. Oracle VM Server also allows you to create up to 128 virtual servers on one system to take advantage of the massive thread scale offered by the CMT architecture. Oracle VM Server for SPARC integrates both the industry-leading CMT capability of the UltraSPARC T1, T2 and T2 Plus processors and the Oracle Solaris operating system. This combination helps to increase flexibility, isolate workload processing, and improve the potential for maximum server utilization. Oracle VM Server for SPARC delivers the following: Leading Price/Performance - The low-overhead architecture provides scalable performance under increasing workloads without additional license cost. This enables you to meet the most aggressive price/performance requirement Advanced RAS - Each logical domain is an entirely independent virtual machine with its own OS. It supports virtual disk mutipathing and failover as well as faster network failover with link-based IP multipathing (IPMP) support. Moreover, it's fully integrated with Solaris FMA (Fault Management Architecture), which enables predictive self healing. CPU Dynamic Resource Management (DRM) - Enable your resource management policy and domain workload to trigger the automatic addition and removal of CPUs. This ability helps you to better align with your IT and business priorities. Enhanced Domain Migrations - Perform domain migrations interactively and non-interactively to bring more flexibility to the management of your virtualized environment. Improve active domain migration performance by compressing memory transfers and taking advantage of cryptographic acceleration hardware. These methods provide faster migration for load balancing, power saving, and planned maintenance. Dynamic Crypto Control - Dynamically add and remove cryptographic units (aka MAU) to and from active domains. Also, migrate active domains that have cryptographic units. Physical-to-virtual (P2V) Conversion - Quickly convert an existing SPARC server running the Oracle Solaris 8, 9 or 10 OS into a virtualized Oracle Solaris 10 image. Use this image to facilitate OS migration into the virtualized environment. Virtual I/O Dynamic Reconfiguration (DR) - Add and remove virtual I/O services and devices without needing to reboot the system. CPU Power Management - Implement power saving by disabling each core on a Sun UltraSPARC T2 or T2 Plus processor that has all of its CPU threads idle. Advanced Network Configuration - Configure the following network features to obtain more flexible network configurations, higher performance, and scalability: Jumbo frames, VLANs, virtual switches for link aggregations, and network interface unit (NIU) hybrid I/O. Official Certification Based On Real-World Testing - Use Oracle VM Server for SPARC with the most sophisticated enterprise workloads under real-world conditions, including Oracle Real Application Clusters (RAC). Affordable, Full-Stack Enterprise Class Support - Obtain worldwide support from Oracle for the entire virtualization environment and workloads together. The support covers hardware, firmware, OS, virtualization, and the software stack. SPARC Server Virtualization Oracle offers a full portfolio of virtualization solutions to address your needs. SPARC is the leading platform to have the hard partitioning capability that provides the physical isolation needed to run independent operating systems. Many customers have already used Oracle Solaris Containers for application isolation. Oracle VM Server for SPARC provides another important feature with OS isolation. This gives you the flexibility to deploy multiple operating systems simultaneously on a single Sun SPARC T-Series server with finer granularity for computing resources.  For SPARC CMT processors, the natural level of granularity is an execution thread, not a time-sliced microsecond of execution resources. Each CPU thread can be treated as an independent virtual processor. The scheduler is naturally built into the CPU for lower overhead and higher performance. Your organizations can couple Oracle Solaris Containers and Oracle VM Server for SPARC with the breakthrough space and energy savings afforded by Sun SPARC Enterprise systems with CMT technology to deliver a more agile, responsive, and low-cost environment. Management with Oracle Enterprise Manager Ops Center The Oracle Enterprise Manager Ops Center Virtualization Management Pack provides full lifecycle management of virtual guests, including Oracle VM Server for SPARC and Oracle Solaris Containers. It helps you streamline operations and reduce downtime. Together, the Virtualization Management Pack and the Ops Center Provisioning and Patch Automation Pack provide an end-to-end management solution for physical and virtual systems through a single web-based console. This solution automates the lifecycle management of physical and virtual systems and is the most effective systems management solution for Oracle's Sun infrastructure. Ease of Deployment with Configuration Assistant The Oracle VM Server for SPARC Configuration Assistant can help you easily create logical domains. After gathering the configuration data, the Configuration Assistant determines the best way to create a deployment to suit your requirements. The Configuration Assistant is available as both a graphical user interface (GUI) and terminal-based tool. Oracle Solaris Cluster HA Support The Oracle Solaris Cluster HA for Oracle VM Server for SPARC data service provides a mechanism for orderly startup and shutdown, fault monitoring and automatic failover of the Oracle VM Server guest domain service. In addition, applications that run on a logical domain, as well as its resources and dependencies can be controlled and managed independently. These are managed as if they were running in a classical Solaris Cluster hardware node. Supported Systems Oracle VM Server for SPARC is supported on all Sun SPARC Enterprise Systems with CMT technology. UltraSPARC T2 Plus Systems ·   Sun SPARC Enterprise T5140 Server ·   Sun SPARC Enterprise T5240 Server ·   Sun SPARC Enterprise T5440 Server ·   Sun Netra T5440 Server ·   Sun Blade T6340 Server Module ·   Sun Netra T6340 Server Module UltraSPARC T2 Systems ·   Sun SPARC Enterprise T5120 Server ·   Sun SPARC Enterprise T5220 Server ·   Sun Netra T5220 Server ·   Sun Blade T6320 Server Module ·   Sun Netra CP3260 ATCA Blade Server Note that UltraSPARC T1 systems are supported on earlier versions of the software.Sun SPARC Enterprise Systems with CMT technology come with the right to use (RTU) of Oracle VM Server, and the software is pre-installed. If you have the systems under warranty or with support, you can download the software and system firmware as well as their updates. Oracle Premier Support for Systems provides fully-integrated support for your server hardware, firmware, OS, and virtualization software. Visit oracle.com/support for information about Oracle's support offerings for Sun systems. For more information about Oracle's virtualization offerings, visit oracle.com/virtualization.

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  • Install Ubuntu Netbook Edition with Wubi Installer

    - by Matthew Guay
    Ubuntu is one of the most popular versions of Linux, and their Netbook Remix edition is especially attractive for netbook owners.  Here we’ll look at how you can easily try out Ubuntu on your netbook without a CD/DVD drive. Netbooks, along with the growing number of thin, full powered laptops, lack a CD/DVD drive.  Installing software isn’t much of a problem since most programs, whether free or for-pay, are available for download.  Operating systems, however, are usually installed from a disk.  You can easily install Windows 7 from a flash drive with our tutorial, but installing Ubuntu from a USB flash drive is more complicated.  However, using Wubi, a Windows installer for Ubuntu, you can easily install it directly on your netbook and even uninstall it with only a few clicks. Getting Started Download and run the Wubi installer for Ubuntu (link below).  In the installer, select the drive you where you wish to install Ubuntu, the size of the installation (this is the amount dedicated to Ubuntu; under 20Gb should be fine), language, username, and desired password.  Also, from the Desktop environment menu, select Ubuntu Netbook to install the netbook edition.  Click Install when your settings are correct. Wubi will automatically download the selected version of Ubuntu and install it on your computer. Windows Firewall may ask if you want to unblock Wubi; select your network and click Allow access. The download will take around an hour on broadband, depending on your internet connection speed.  Once the download is completed, it will automatically install to your computer.  If you’d prefer to have everything downloaded before you start the install, download the ISO of Ubuntu Netbook edition (link below) and save it in the same folder as Wubi. Then, when you run Wubi, select the netbook edition as before and click Install.  Wubi will verify that your download is valid, and will then proceed to install from the downloaded ISO.  This install will only take about 10 minutes. Once the install is finished you will be asked to reboot your computer.  Save anything else you’re working on, and then reboot to finish setting up Ubuntu on your netbook. When your computer reboots, select Ubuntu at the boot screen.  Wubi leaves the default OS as Windows 7, so if you don’t select anything it will boot into Windows 7 after a few seconds. Ubuntu will automatically finish the install when you boot into it the first time.  This took about 12 minutes in our test. When the setup is finished, your netbook will reboot one more time.  Remember again to select Ubuntu at the boot screen.  You’ll then see a second boot screen; press your Enter key to select the default.   Ubuntu only took less than a minute to boot in our test.  When you see the login screen, select your name and enter your password you setup in Wubi.  Now you’re ready to start exploring Ubuntu Netbook Remix. Using Ubuntu Netbook Remix Ubuntu Netbook Remix offers a simple, full-screen interface to take the best advantage of netbooks’ small screens.  Pre-installed applications are displayed in the application launcher, and are organized by category.  Click once to open an application. The first screen on the application launcher shows your favorite programs.  If you’d like to add another application to the favorites pane, click the plus sign beside its icon. Your files from Windows are still accessible from Ubuntu Netbook Remix.  From the home screen, select Files & Folders on the left menu, and then click the icon that says something like 100GB Filesystem under the Volumes section. Now you’ll be able to see all of your files from Windows.  Your user files such as documents, music, and pictures should be located in Documents and Settings in a folder with your user name. You can also easily install a variety of free applications via the Software Installer. Connecting to the internet is also easy, as Ubuntu Netbook Remix automatically recognized the WiFi adaptor on our test netbook, a Samsung N150.  To connect to a wireless network, click the wireless icon on the top right of the screen and select the network’s name from the list. And, if you’d like to customize your screen, right-click on the application launcher and select Change desktop background. Choose a background picture you’d like. Now you’ll see it through your application launcher.  Nice! Most applications are opened full-screen.  You can close them by clicking the x on the right of the program’s name. You can also switch to other applications from their icons on the top left.  Open the home screen by clicking the Ubuntu logo in the far left. Changing Boot Options By default, Wubi will leave Windows as the default operating system, and will give you 10 seconds at boot to choose to boot into Ubuntu.  To change this, boot into Windows and enter Advanced system settings in your start menu search. In this dialog, click Settings under Startup and Recovery. From this dialog, you can select the default operating system and the time to display list of operating systems.  You can enter a lower number to make the boot screen appear for less time. And if you’d rather make Ubuntu the default operating system, select it from the drop-down list.   Uninstalling Ubuntu Netbook Remix If you decide you don’t want to keep Ubuntu Netbook Remix on your computer, you can uninstall it just like you uninstall any normal application.  Boot your computer into Windows, open Control Panel, click Uninstall a Program, and enter ubuntu in the search box.  Select it, and click Uninstall. Click Uninstall at the prompt.  Ubuntu uninstalls very quickly, and removes the entry from the bootloader as well, so your computer is just like it was before you installed it.   Conclusion Ubuntu Netbook Remix offers an attractive Linux interface for netbooks.  We enjoyed trying it out, and found it much more user-friendly than most Linux distros.  And with the Wubi installer, you can install it risk-free and try it out on your netbook.  Or, if you’d like to try out another alternate netbook operating system, check out our article on Jolicloud, another new OS for netbooks. Links Download Wubi Installer for Windows Download Ubuntu Netbook Edition Similar Articles Productive Geek Tips Easily Install Ubuntu Linux with Windows Using the Wubi InstallerInstall VMware Tools on Ubuntu Edgy EftHow to install Spotify in Ubuntu 9.10 using WineInstalling PHP5 and Apache on UbuntuInstalling PHP4 and Apache on Ubuntu TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips VMware Workstation 7 Acronis Online Backup DVDFab 6 Revo Uninstaller Pro Explorer++ is a Worthy Windows Explorer Alternative Error Goblin Explains Windows Error Codes Twelve must-have Google Chrome plugins Cool Looking Skins for Windows Media Player 12 Move the Mouse Pointer With Your Face Movement Using eViacam Boot Windows Faster With Boot Performance Diagnostics

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  • Microsoft TypeScript : A Typed Superset of JavaScript

    - by shiju
    JavaScript is gradually becoming a ubiquitous programming language for the web, and the popularity of JavaScript is increasing day by day. Earlier, JavaScript was just a language for browser. But now, we can write JavaScript apps for browser, server and mobile. With the advent of Node.js, you can build scalable, high performance apps on the server with JavaScript. But many developers, especially developers who are working with static type languages, are hating the JavaScript language due to the lack of structuring and the maintainability problems of JavaScript. Microsoft TypeScript is trying to solve some problems of JavaScript when we are building scalable JavaScript apps. Microsoft TypeScript TypeScript is Microsoft's solution for writing scalable JavaScript programs with the help of Static Types, Interfaces, Modules and Classes along with greater tooling support. TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. This would be more productive for developers who are coming from static type languages. You can write scalable JavaScript  apps in TypeScript with more productive and more maintainable manner, and later you can compiles to plain JavaScript which will be run on any browser and any OS. TypeScript will work with browser based JavaScript apps and JavaScript apps that following CommonJS specification. You can use TypeScript for building HTML 5 apps, Node.JS apps, WinRT apps. TypeScript is providing better tooling support with Visual Studio, Sublime Text, Vi, Emacs. Microsoft has open sourced its TypeScript languages on CodePlex at http://typescript.codeplex.com/    Install TypeScript You can install TypeScript compiler as a Node.js package via the NPM or you can install as a Visual Studio 2012 plug-in which will enable you better tooling support within the Visual Studio IDE. Since TypeScript is distributed as a Node.JS package, and it can be installed on other OS such as Linux and MacOS. The following command will install TypeScript compiler via an npm package for node.js npm install –g typescript TypeScript provides a Visual Studio 2012 plug-in as MSI file which will install TypeScript and also provides great tooling support within the Visual Studio, that lets the developers to write TypeScript apps with greater productivity and better maintainability. You can download the Visual Studio plug-in from here Building JavaScript  apps with TypeScript You can write typed version of JavaScript programs with TypeScript and then compiles it to plain JavaScript code. The beauty of the TypeScript is that it is already JavaScript and normal JavaScript programs are valid TypeScript programs, which means that you can write normal  JavaScript code and can use typed version of JavaScript whenever you want. TypeScript files are using extension .ts and this will be compiled using a compiler named tsc. The following is a sample program written in  TypeScript greeter.ts 1: class Greeter { 2: greeting: string; 3: constructor (message: string) { 4: this.greeting = message; 5: } 6: greet() { 7: return "Hello, " + this.greeting; 8: } 9: } 10:   11: var greeter = new Greeter("world"); 12:   13: var button = document.createElement('button') 14: button.innerText = "Say Hello" 15: button.onclick = function() { 16: alert(greeter.greet()) 17: } 18:   19: document.body.appendChild(button) .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The above program is compiling with the TypeScript compiler as shown in the below picture The TypeScript compiler will generate a JavaScript file after compiling the TypeScript program. If your TypeScript programs having any reference to other TypeScript files, it will automatically generate JavaScript files for the each referenced files. The following code block shows the compiled version of plain JavaScript  for the above greeter.ts greeter.js 1: var Greeter = (function () { 2: function Greeter(message) { 3: this.greeting = message; 4: } 5: Greeter.prototype.greet = function () { 6: return "Hello, " + this.greeting; 7: }; 8: return Greeter; 9: })(); 10: var greeter = new Greeter("world"); 11: var button = document.createElement('button'); 12: button.innerText = "Say Hello"; 13: button.onclick = function () { 14: alert(greeter.greet()); 15: }; 16: document.body.appendChild(button); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Tooling Support with Visual Studio TypeScript is providing a plug-in for Visual Studio which will provide an excellent support for writing TypeScript  programs within the Visual Studio. The following screen shot shows the Visual Studio template for TypeScript apps   The following are the few screen shots of Visual Studio IDE for TypeScript apps. Summary TypeScript is Microsoft's solution for writing scalable JavaScript apps which will solve lot of problems involved in larger JavaScript apps. I hope that this solution will attract lot of developers who are really looking for writing maintainable structured code in JavaScript, without losing any productivity. TypeScript lets developers to write JavaScript apps with the help of Static Types, Interfaces, Modules and Classes and also providing better productivity. I am a passionate developer on Node.JS and would definitely try to use TypeScript for building Node.JS apps on the Windows Azure cloud. I am really excited about to writing Node.JS apps by using TypeScript, from my favorite development IDE Visual Studio. You can follow me on twitter at @shijucv

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  • BNF – how to read syntax?

    - by Piotr Rodak
    A few days ago I read post of Jen McCown (blog) about her idea of blogging about random articles from Books Online. I think this is a great idea, even if Jen says that it’s not exciting or sexy. I noticed that many of the questions that appear on forums and other media arise from pure fact that people asking questions didn’t bother to read and understand the manual – Books Online. Jen came up with a brilliant, concise acronym that describes very well the category of posts about Books Online – RTFM365. I take liberty of tagging this post with the same acronym. I often come across questions of type – ‘Hey, i am trying to create a table, but I am getting an error’. The error often says that the syntax is invalid. 1 CREATE TABLE dbo.Employees 2 (guid uniqueidentifier CONSTRAINT DEFAULT Guid_Default NEWSEQUENTIALID() ROWGUIDCOL, 3 Employee_Name varchar(60) 4 CONSTRAINT Guid_PK PRIMARY KEY (guid) ); 5 The answer is usually(1), ‘Ok, let me check it out.. Ah yes – you have to put name of the DEFAULT constraint before the type of constraint: 1 CREATE TABLE dbo.Employees 2 (guid uniqueidentifier CONSTRAINT Guid_Default DEFAULT NEWSEQUENTIALID() ROWGUIDCOL, 3 Employee_Name varchar(60) 4 CONSTRAINT Guid_PK PRIMARY KEY (guid) ); Why many people stumble on syntax errors? Is the syntax poorly documented? No, the issue is, that correct syntax of the CREATE TABLE statement is documented very well in Books Online and is.. intimidating. Many people can be taken aback by the rather complex block of code that describes all intricacies of the statement. However, I don’t know better way of defining syntax of the statement or command. The notation that is used to describe syntax in Books Online is a form of Backus-Naur notatiion, called BNF for short sometimes. This is a notation that was invented around 50 years ago, and some say that even earlier, around 400 BC – would you believe? Originally it was used to define syntax of, rather ancient now, ALGOL programming language (in 1950’s, not in ancient India). If you look closer at the definition of the BNF, it turns out that the principles of this syntax are pretty simple. Here are a few bullet points: italic_text is a placeholder for your identifier <italic_text_in_angle_brackets> is a definition which is described further. [everything in square brackets] is optional {everything in curly brackets} is obligatory everything | separated | by | operator is an alternative ::= “assigns” definition to an identifier Yes, it looks like these six simple points give you the key to understand even the most complicated syntax definitions in Books Online. Books Online contain an article about syntax conventions – have you ever read it? Let’s have a look at fragment of the CREATE TABLE statement: 1 CREATE TABLE 2 [ database_name . [ schema_name ] . | schema_name . ] table_name 3 ( { <column_definition> | <computed_column_definition> 4 | <column_set_definition> } 5 [ <table_constraint> ] [ ,...n ] ) 6 [ ON { partition_scheme_name ( partition_column_name ) | filegroup 7 | "default" } ] 8 [ { TEXTIMAGE_ON { filegroup | "default" } ] 9 [ FILESTREAM_ON { partition_scheme_name | filegroup 10 | "default" } ] 11 [ WITH ( <table_option> [ ,...n ] ) ] 12 [ ; ] Let’s look at line 2 of the above snippet: This line uses rules 3 and 5 from the list. So you know that you can create table which has specified one of the following. just name – table will be created in default user schema schema name and table name – table will be created in specified schema database name, schema name and table name – table will be created in specified database, in specified schema database name, .., table name – table will be created in specified database, in default schema of the user. Note that this single line of the notation describes each of the naming schemes in deterministic way. The ‘optionality’ of the schema_name element is nested within database_name.. section. You can use either database_name and optional schema name, or just schema name – this is specified by the pipe character ‘|’. The error that user gets with execution of the first script fragment in this post is as follows: Msg 156, Level 15, State 1, Line 2 Incorrect syntax near the keyword 'DEFAULT'. Ok, let’s have a look how to find out the correct syntax. Line number 3 of the BNF fragment above contains reference to <column_definition>. Since column_definition is in angle brackets, we know that this is a reference to notion described further in the code. And indeed, the very next fragment of BNF contains syntax of the column definition. 1 <column_definition> ::= 2 column_name <data_type> 3 [ FILESTREAM ] 4 [ COLLATE collation_name ] 5 [ NULL | NOT NULL ] 6 [ 7 [ CONSTRAINT constraint_name ] DEFAULT constant_expression ] 8 | [ IDENTITY [ ( seed ,increment ) ] [ NOT FOR REPLICATION ] 9 ] 10 [ ROWGUIDCOL ] [ <column_constraint> [ ...n ] ] 11 [ SPARSE ] Look at line 7 in the above fragment. It says, that the column can have a DEFAULT constraint which, if you want to name it, has to be prepended with [CONSTRAINT constraint_name] sequence. The name of the constraint is optional, but I strongly recommend you to make the effort of coming up with some meaningful name yourself. So the correct syntax of the CREATE TABLE statement from the beginning of the article is like this: 1 CREATE TABLE dbo.Employees 2 (guid uniqueidentifier CONSTRAINT Guid_Default DEFAULT NEWSEQUENTIALID() ROWGUIDCOL, 3 Employee_Name varchar(60) 4 CONSTRAINT Guid_PK PRIMARY KEY (guid) ); That is practically everything you should know about BNF. I encourage you to study the syntax definitions for various statements and commands in Books Online, you can find really interesting things hidden there. Technorati Tags: SQL Server,t-sql,BNF,syntax   (1) No, my answer usually is a question – ‘What error message? What does it say?’. You’d be surprised to know how many people think I can go through time and space and look at their screen at the moment they received the error.

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  • Sending Messages to SignalR Hubs from the Outside

    - by Ricardo Peres
    Introduction You are by now probably familiarized with SignalR, Microsoft’s API for real-time web functionality. This is, in my opinion, one of the greatest products Microsoft has released in recent time. Usually, people login to a site and enter some page which is connected to a SignalR hub. Then they can send and receive messages – not just text messages, mind you – to other users in the same hub. Also, the server can also take the initiative to send messages to all or a specified subset of users on its own, this is known as server push. The normal flow is pretty straightforward, Microsoft has done a great job with the API, it’s clean and quite simple to use. And for the latter – the server taking the initiative – it’s also quite simple, just involves a little more work. The Problem The API for sending messages can be achieved from inside a hub – an instance of the Hub class – which is something that we don’t have if we are the server and we want to send a message to some user or group of users: the Hub instance is only instantiated in response to a client message. The Solution It is possible to acquire a hub’s context from outside of an actual Hub instance, by calling GlobalHost.ConnectionManager.GetHubContext<T>(). This API allows us to: Broadcast messages to all connected clients (possibly excluding some); Send messages to a specific client; Send messages to a group of clients. So, we have groups and clients, each is identified by a string. Client strings are called connection ids and group names are free-form, given by us. The problem with client strings is, we do not know how these map to actual users. One way to achieve this mapping is by overriding the Hub’s OnConnected and OnDisconnected methods and managing the association there. Here’s an example: 1: public class MyHub : Hub 2: { 3: private static readonly IDictionary<String, ISet<String>> users = new ConcurrentDictionary<String, ISet<String>>(); 4:  5: public static IEnumerable<String> GetUserConnections(String username) 6: { 7: ISet<String> connections; 8:  9: users.TryGetValue(username, out connections); 10:  11: return (connections ?? Enumerable.Empty<String>()); 12: } 13:  14: private static void AddUser(String username, String connectionId) 15: { 16: ISet<String> connections; 17:  18: if (users.TryGetValue(username, out connections) == false) 19: { 20: connections = users[username] = new HashSet<String>(); 21: } 22:  23: connections.Add(connectionId); 24: } 25:  26: private static void RemoveUser(String username, String connectionId) 27: { 28: users[username].Remove(connectionId); 29: } 30:  31: public override Task OnConnected() 32: { 33: AddUser(this.Context.Request.User.Identity.Name, this.Context.ConnectionId); 34: return (base.OnConnected()); 35: } 36:  37: public override Task OnDisconnected() 38: { 39: RemoveUser(this.Context.Request.User.Identity.Name, this.Context.ConnectionId); 40: return (base.OnDisconnected()); 41: } 42: } As you can see, I am using a static field to store the mapping between a user and its possibly many connections – for example, multiple open browser tabs or even multiple browsers accessing the same page with the same login credentials. The user identity, as is normal in .NET, is obtained from the IPrincipal which in SignalR hubs case is stored in Context.Request.User. Of course, this property will only have a meaningful value if we enforce authentication. Another way to go is by creating a group for each user that connects: 1: public class MyHub : Hub 2: { 3: public override Task OnConnected() 4: { 5: this.Groups.Add(this.Context.ConnectionId, this.Context.Request.User.Identity.Name); 6: return (base.OnConnected()); 7: } 8:  9: public override Task OnDisconnected() 10: { 11: this.Groups.Remove(this.Context.ConnectionId, this.Context.Request.User.Identity.Name); 12: return (base.OnDisconnected()); 13: } 14: } In this case, we will have a one-to-one equivalence between users and groups. All connections belonging to the same user will fall in the same group. So, if we want to send messages to a user from outside an instance of the Hub class, we can do something like this, for the first option – user mappings stored in a static field: 1: public void SendUserMessage(String username, String message) 2: { 3: var context = GlobalHost.ConnectionManager.GetHubContext<MyHub>(); 4: 5: foreach (String connectionId in HelloHub.GetUserConnections(username)) 6: { 7: context.Clients.Client(connectionId).sendUserMessage(message); 8: } 9: } And for using groups, its even simpler: 1: public void SendUserMessage(String username, String message) 2: { 3: var context = GlobalHost.ConnectionManager.GetHubContext<MyHub>(); 4:  5: context.Clients.Group(username).sendUserMessage(message); 6: } Using groups has the advantage that the IHubContext interface returned from GetHubContext has direct support for groups, no need to send messages to individual connections. Of course, you can wrap both mapping options in a common API, perhaps exposed through IoC. One example of its interface might be: 1: public interface IUserToConnectionMappingService 2: { 3: //associate and dissociate connections to users 4:  5: void AddUserConnection(String username, String connectionId); 6:  7: void RemoveUserConnection(String username, String connectionId); 8: } SignalR has built-in dependency resolution, by means of the static GlobalHost.DependencyResolver property: 1: //for using groups (in the Global class) 2: GlobalHost.DependencyResolver.Register(typeof(IUserToConnectionMappingService), () => new GroupsMappingService()); 3:  4: //for using a static field (in the Global class) 5: GlobalHost.DependencyResolver.Register(typeof(IUserToConnectionMappingService), () => new StaticMappingService()); 6:  7: //retrieving the current service (in the Hub class) 8: var mapping = GlobalHost.DependencyResolver.Resolve<IUserToConnectionMappingService>(); Now all you have to do is implement GroupsMappingService and StaticMappingService with the code I shown here and change SendUserMessage method to rely in the dependency resolver for the actual implementation. Stay tuned for more SignalR posts!

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  • Building services with the .NET framework Cont’d

    - by Allan Rwakatungu
    In my previous blog I wrote an introductory post on services and how you can build services using the .NET frameworks Windows Communication Foundation (WCF) In this post I will show how to develop a real world application using WCF The problem During the last meeting we realized developers in Uganda are not so cool – they don’t use twitter so may not get the latest news and updates from the technology world. We also noticed they mostly use kabiriti phones (jokes). With their kabiriti phones they are unable to access the twitter web client or alternative twitter mobile clients like tweetdeck , twirl or tweetie. However, the kabiriti phones support SMS (Yeeeeeeei). So what we going to do to make these developers cool and keep them updated is by enabling them to receive tweets via SMS. We shall also enable them to develop their own applications that can extend this functionality Analysis Thanks to services and open API’s solving our problem is going to be easy.  1. To get tweets we can use the twitter service for FREE 2. To send SMS we shall use www.clickatell.com/ as they can send SMS to any country in the world. Besides we could not find any local service that offers API's for sending SMS :(. 3. To enable developers to integrate with our application so that they can extend it and build even cooler applications we use WCF. In addittion , because connectivity might be an issue we decided to use WCF because if has a inbuilt queing features. We also choose WCF because this is a post about .NET and WCF :). The Code Accessing the tweets To consume twitters REST API we shall use the WCF REST starter kit. Like it name indicates , the REST starter kit is a set of .NET framework classes that enable developers to create and access REST style services ( like the twitter service). Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Http; using System.Net; using System.Xml.Linq;   namespace UG.Demo {     public class TwitterService     {         public IList<TwitterStatus> SomeMethodName()         {             //Connect to the twitter service (HttpClient is part of the REST startkit classes)             HttpClient cl = new HttpClient("http://api.twitter.com/1/statuses/friends_timeline.xml");             //Supply your basic authentication credentials             cl.TransportSettings.Credentials = new NetworkCredential("ourusername", "ourpassword");             //issue an http             HttpResponseMessage resp = cl.Get();             //ensure we got reponse 200             resp.EnsureStatusIsSuccessful();             //use XLinq to parse the REST XML             var statuses = from r in resp.Content.ReadAsXElement().Descendants("status")                            select new TwitterStatus                            {                                User = r.Element("user").Element("screen_name").Value,                                Status = r.Element("text").Value                            };             return statuses.ToList();         }     }     public class TwitterStatus     {         public string User { get; set; }         public string Status { get; set; }     } }  Sending SMS Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} public class SMSService     {         public void Send(string phone, string message)         {                         HttpClient cl1 = new HttpClient();              //the clickatell XML format for sending SMS             string xml = String.Format("<clickAPI><sendMsg><api_id>3239621</api_id><user>ourusername</user><password>ourpassword</password><to>{0}</to><text>{1}</text></sendMsg></clickAPI>",phone,message);             //Post form data             HttpUrlEncodedForm form = new HttpUrlEncodedForm();             form.Add("data", xml);             System.Net.ServicePointManager.Expect100Continue = false;             string uri = @"http://api.clickatell.com/xml/xml";             HttpResponseMessage resp = cl1.Post(uri, form.CreateHttpContent());             resp.EnsureStatusIsSuccessful();         }     }

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  • Interface contracts – forcing code contracts through interfaces

    - by DigiMortal
    Sometimes we need a way to make different implementations of same interface follow same rules. One option is to duplicate contracts to all implementation but this is not good option because we have duplicated code then. The other option is to force contracts to all implementations at interface level. In this posting I will show you how to do it using interface contracts and contracts class. Using code from previous example about unit testing code with code contracts I will go further and force contracts at interface level. Here is the code from previous example. Take a careful look at it because I will talk about some modifications to this code soon. public interface IRandomGenerator {     int Next(int min, int max); }   public class RandomGenerator : IRandomGenerator {     private Random _random = new Random();       public int Next(int min, int max)     {         return _random.Next(min, max);     } }    public class Randomizer {     private IRandomGenerator _generator;       private Randomizer()     {         _generator = new RandomGenerator();     }       public Randomizer(IRandomGenerator generator)     {         _generator = generator;     }       public int GetRandomFromRangeContracted(int min, int max)     {         Contract.Requires<ArgumentOutOfRangeException>(             min < max,             "Min must be less than max"         );           Contract.Ensures(             Contract.Result<int>() >= min &&             Contract.Result<int>() <= max,             "Return value is out of range"         );           return _generator.Next(min, max);     } } If we look at the GetRandomFromRangeContracted() method we can see that contracts set in this method are applicable to all implementations of IRandomGenerator interface. Although we can write new implementations as we want these implementations need exactly the same contracts. If we are using generators somewhere else then code contracts are not with them anymore. To solve the problem we will force code contracts at interface level. NB! To make the following code work you must enable Contract Reference Assembly building from project settings. Interface contracts and contracts class Interface contains no code – only definitions of members that implementing type must have. But code contracts must be defined in body of member they are part of. To get over this limitation, code contracts are defined in separate contracts class. Interface is bound to this class by special attribute and contracts class refers to interface through special attribute. Here is the IRandomGenerator with contracts and contracts class. Also I write simple fake so we can test contracts easily based only on interface mock. [ContractClass(typeof(RandomGeneratorContracts))] public interface IRandomGenerator {     int Next(int min, int max); }   [ContractClassFor(typeof(IRandomGenerator))] internal sealed class RandomGeneratorContracts : IRandomGenerator {     int IRandomGenerator.Next(int min, int max)     {         Contract.Requires<ArgumentOutOfRangeException>(                 min < max,                 "Min must be less than max"             );           Contract.Ensures(             Contract.Result<int>() >= min &&             Contract.Result<int>() <= max,             "Return value is out of range"         );           return default(int);     } }   public class RandomFake : IRandomGenerator {     private int _testValue;       public RandomGen(int testValue)     {         _testValue = testValue;     }       public int Next(int min, int max)     {         return _testValue;     } } To try out these changes use the following code. var gen = new RandomFake(3);   try {     gen.Next(10, 1); } catch(Exception ex) {     Debug.WriteLine(ex.Message); }   try {     gen.Next(5, 10); } catch(Exception ex) {     Debug.WriteLine(ex.Message); } Now we can force code contracts to all types that implement our IRandomGenerator interface and we must test only the interface to make sure that contracts are defined correctly.

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  • Using Teleriks new LINQ implementation to create OData feeds

    This week Telerik released a new LINQ implementation that is simple to use and produces domain models very fast. Built on top of the enterprise grade OpenAccess ORM, you can connect to any database that OpenAccess can connect to such as: SQL Server, MySQL, Oracle, SQL Azure, VistaDB, etc. While this is a separate LINQ implementation from traditional OpenAccess Entites, you can use the visual designer without ever interacting with OpenAccess, however, you can always hook into the advanced ORM features like caching, fetch plan optimization, etc, if needed. Just to show off how easy our LINQ implementation is to use, I will walk you through building an OData feed using Data Services Update for .NET Framework 3.5 SP1. (Memo to Microsoft: P-L-E-A-S-E hire someone from Apple to name your products.) How easy is it? If you have a fast machine, are skilled with the mouse, and type fast, you can do this in about 60 seconds via three easy steps. (I promise in about 2-3 weeks that you can do this in less then 30 seconds. Stay tuned for that.)  Step 1 (15-20 seconds): Building your Domain Model In your web project in Visual Studio, right click on the project and select Add|New Item and select Telerik OpenAccess Domain Model as your item template. Give the file a meaningful name as well. Select your database type (SQL Server, SQL Azure, Oracle, MySQL, VistaDB, etc) and build the connection string. If you already have a Visual Studio connection string already saved, this step is trivial.  Then select your tables, enter a name for your model and click Finish. In this case I connected to Northwind and selected only Customers, Orders, and Order Details.  I named my model NorthwindEntities and will use that in my DataService. Step 2 (20-25 seconds): Adding and Configuring your Data Service In your web project in Visual Studio, right click on the project and select Add|New Item and select ADO .NET Data Service as your item template and name your service. In the code behind for your Data Service you have to make three small changes. Add the name of your Telerik Domain Model (entered in Step 1) as the DataService name (shown on line 6 below as NorthwindEntities) and uncomment line 11 and add a * to show all entities. Optionally if you want to take advantage of the DataService 3.5 updates, add line 13 (and change IDataServiceConfiguration to DataServiceConfiguration in line 9.) 1: using System.Data.Services; 2: using System.Data.Services.Common; 3:   4: namespace Telerik.RLINQ.Astoria.Web 5: { 6: public class NorthwindService : DataService<NorthwindEntities> 7: { 8: //change the IDataServiceConfigurationto DataServiceConfiguration 9: public static void InitializeService(DataServiceConfiguration config) 10: { 11: config.SetEntitySetAccessRule("*", EntitySetRights.All); 12: //take advantage of the "Astoria3.5 Update" features 13: config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; 14: } 15: } 16: } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Step 3 (~30 seconds): Adding the DataServiceKeys You now have to tell your data service what are the primary keys of each entity. To do this you have to create a new code file and create a few partial classes. If you type fast, use copy and paste from your first entity,  and use a refactoring productivity tool, you can add these 6-8 lines of code or so in about 30 seconds. This is the most tedious step, but dont worry, Ive bribed some of the developers and our next update will eliminate this step completely. Just create a partial class for each entity you have mapped and add the attribute [DataServiceKey] on top of it along with the keys field name. If you have any complex properties, you will need to make them a primitive type, as I do in line 15. Create this as a separate file, dont manipulate the generated data access classes in case you want to regenerate them again later (even thought that would be much faster.) 1: using System.Data.Services.Common; 2:   3: namespace Telerik.RLINQ.Astoria.Web 4: { 5: [DataServiceKey("CustomerID")] 6: public partial class Customer 7: { 8: } 9:   10: [DataServiceKey("OrderID")] 11: public partial class Order 12: { 13: } 14:   15: [DataServiceKey(new string[] { "OrderID", "ProductID" })] 16: public partial class OrderDetail 17: { 18: } 19:   20: } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Done! Time to run the service. Now, lets run the service! Select the svc file and right click and say View in Browser. You will see your OData service and can interact with it in the browser. Now that you have an OData service set up, you can consume it in one of the many ways that OData is consumed: using LINQ, the Silverlight OData client, Excel PowerPivot, or PhP, etc. Happy Data Servicing! Technorati Tags: Telerik,Astoria,Data Services Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • What's up with LDoms: Part 4 - Virtual Networking Explained

    - by Stefan Hinker
    I'm back from my summer break (and some pressing business that kept me away from this), ready to continue with Oracle VM Server for SPARC ;-) In this article, we'll have a closer look at virtual networking.  Basic connectivity as we've seen it in the first, simple example, is easy enough.  But there are numerous options for the virtual switches and virtual network ports, which we will discuss in more detail now.   In this section, we will concentrate on virtual networking - the capabilities of virtual switches and virtual network ports - only.  Other options involving hardware assignment or redundancy will be covered in separate sections later on. There are two basic components involved in virtual networking for LDoms: Virtual switches and virtual network devices.  The virtual switch should be seen just like a real ethernet switch.  It "runs" in the service domain and moves ethernet packets back and forth.  A virtual network device is plumbed in the guest domain.  It corresponds to a physical network device in the real world.  There, you'd be plugging a cable into the network port, and plug the other end of that cable into a switch.  In the virtual world, you do the same:  You create a virtual network device for your guest and connect it to a virtual switch in a service domain.  The result works just like in the physical world, the network device sends and receives ethernet packets, and the switch does all those things ethernet switches tend to do. If you look at the reference manual of Oracle VM Server for SPARC, there are numerous options for virtual switches and network devices.  Don't be confused, it's rather straight forward, really.  Let's start with the simple case, and work our way to some more sophisticated options later on.  In many cases, you'll want to have several guests that communicate with the outside world on the same ethernet segment.  In the real world, you'd connect each of these systems to the same ethernet switch.  So, let's do the same thing in the virtual world: root@sun # ldm add-vsw net-dev=nxge2 admin-vsw primary root@sun # ldm add-vnet admin-net admin-vsw mars root@sun # ldm add-vnet admin-net admin-vsw venus We've just created a virtual switch called "admin-vsw" and connected it to the physical device nxge2.  In the physical world, we'd have powered up our ethernet switch and installed a cable between it and our big enterprise datacenter switch.  We then created a virtual network interface for each one of the two guest systems "mars" and "venus" and connected both to that virtual switch.  They can now communicate with each other and with any system reachable via nxge2.  If primary were running Solaris 10, communication with the guests would not be possible.  This is different with Solaris 11, please see the Admin Guide for details.  Note that I've given both the vswitch and the vnet devices some sensible names, something I always recommend. Unless told otherwise, the LDoms Manager software will automatically assign MAC addresses to all network elements that need one.  It will also make sure that these MAC addresses are unique and reuse MAC addresses to play nice with all those friendly DHCP servers out there.  However, if we want to do this manually, we can also do that.  (One reason might be firewall rules that work on MAC addresses.)  So let's give mars a manually assigned MAC address: root@sun # ldm set-vnet mac-addr=0:14:4f:f9:c4:13 admin-net mars Within the guest, these virtual network devices have their own device driver.  In Solaris 10, they'd appear as "vnet0".  Solaris 11 would apply it's usual vanity naming scheme.  We can configure these interfaces just like any normal interface, give it an IP-address and configure sophisticated routing rules, just like on bare metal.  In many cases, using Jumbo Frames helps increase throughput performance.  By default, these interfaces will run with the standard ethernet MTU of 1500 bytes.  To change this,  it is usually sufficient to set the desired MTU for the virtual switch.  This will automatically set the same MTU for all vnet devices attached to that switch.  Let's change the MTU size of our admin-vsw from the example above: root@sun # ldm set-vsw mtu=9000 admin-vsw primary Note that that you can set the MTU to any value between 1500 and 16000.  Of course, whatever you set needs to be supported by the physical network, too. Another very common area of network configuration is VLAN tagging. This can be a little confusing - my advise here is to be very clear on what you want, and perhaps draw a little diagram the first few times.  As always, keeping a configuration simple will help avoid errors of all kind.  Nevertheless, VLAN tagging is very usefull to consolidate different networks onto one physical cable.  And as such, this concept needs to be carried over into the virtual world.  Enough of the introduction, here's a little diagram to help in explaining how VLANs work in LDoms: Let's remember that any VLANs not explicitly tagged have the default VLAN ID of 1. In this example, we have a vswitch connected to a physical network that carries untagged traffic (VLAN ID 1) as well as VLANs 11, 22, 33 and 44.  There might also be other VLANs on the wire, but the vswitch will ignore all those packets.  We also have two vnet devices, one for mars and one for venus.  Venus will see traffic from VLANs 33 and 44 only.  For VLAN 44, venus will need to configure a tagged interface "vnet44000".  For VLAN 33, the vswitch will untag all incoming traffic for venus, so that venus will see this as "normal" or untagged ethernet traffic.  This is very useful to simplify guest configuration and also allows venus to perform Jumpstart or AI installations over this network even if the Jumpstart or AI server is connected via VLAN 33.  Mars, on the other hand, has full access to untagged traffic from the outside world, and also to VLANs 11,22 and 33, but not 44.  On the command line, we'd do this like this: root@sun # ldm add-vsw net-dev=nxge2 pvid=1 vid=11,22,33,44 admin-vsw primary root@sun # ldm add-vnet admin-net pvid=1 vid=11,22,33 admin-vsw mars root@sun # ldm add-vnet admin-net pvid=33 vid=44 admin-vsw venus Finally, I'd like to point to a neat little option that will make your live easier in all those cases where configurations tend to change over the live of a guest system.  It's the "id=<somenumber>" option available for both vswitches and vnet devices.  Normally, Solaris in the guest would enumerate network devices sequentially.  However, it has ways of remembering this initial numbering.  This is good in the physical world.  In the virtual world, whenever you unbind (aka power off and disassemble) a guest system, remove and/or add network devices and bind the system again, chances are this numbering will change.  Configuration confusion will follow suit.  To avoid this, nail down the initial numbering by assigning each vnet device it's device-id explicitly: root@sun # ldm add-vnet admin-net id=1 admin-vsw venus Please consult the Admin Guide for details on this, and how to decipher these network ids from Solaris running in the guest. Thanks for reading this far.  Links for further reading are essentially only the Admin Guide and Reference Manual and can be found above.  I hope this is useful and, as always, I welcome any comments.

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  • Listing common SQL Code Smells.

    - by Phil Factor
    Once you’ve done a number of SQL Code-reviews, you’ll know those signs in the code that all might not be well. These ’Code Smells’ are coding styles that don’t directly cause a bug, but are indicators that all is not well with the code. . Kent Beck and Massimo Arnoldi seem to have coined the phrase in the "OnceAndOnlyOnce" page of www.C2.com, where Kent also said that code "wants to be simple". Bad Smells in Code was an essay by Kent Beck and Martin Fowler, published as Chapter 3 of the book ‘Refactoring: Improving the Design of Existing Code’ (ISBN 978-0201485677) Although there are generic code-smells, SQL has its own particular coding habits that will alert the programmer to the need to re-factor what has been written. See Exploring Smelly Code   and Code Deodorants for Code Smells by Nick Harrison for a grounding in Code Smells in C# I’ve always been tempted by the idea of automating a preliminary code-review for SQL. It would be so useful to trawl through code and pick up the various problems, much like the classic ‘Lint’ did for C, and how the Code Metrics plug-in for .NET Reflector by Jonathan 'Peli' de Halleux is used for finding Code Smells in .NET code. The problem is that few of the standard procedural code smells are relevant to SQL, and we need an agreed list of code smells. Merrilll Aldrich made a grand start last year in his blog Top 10 T-SQL Code Smells.However, I'd like to make a start by discovering if there is a general opinion amongst Database developers what the most important SQL Smells are. One can be a bit defensive about code smells. I will cheerfully write very long stored procedures, even though they are frowned on. I’ll use dynamic SQL occasionally. You can only use them as an aid for your own judgment and it is fine to ‘sign them off’ as being appropriate in particular circumstances. Also, whole classes of ‘code smells’ may be irrelevant for a particular database. The use of proprietary SQL, for example, is only a ‘code smell’ if there is a chance that the database will have to be ported to another RDBMS. The use of dynamic SQL is a risk only with certain security models. As the saying goes,  a CodeSmell is a hint of possible bad practice to a pragmatist, but a sure sign of bad practice to a purist. Plamen Ratchev’s wonderful article Ten Common SQL Programming Mistakes lists some of these ‘code smells’ along with out-and-out mistakes, but there are more. The use of nested transactions, for example, isn’t entirely incorrect, even though the database engine ignores all but the outermost: but it does flag up the possibility that the programmer thinks that nested transactions are supported. If anything requires some sort of general agreement, the definition of code smells is one. I’m therefore going to make this Blog ‘dynamic, in that, if anyone twitters a suggestion with a #SQLCodeSmells tag (or sends me a twitter) I’ll update the list here. If you add a comment to the blog with a suggestion of what should be added or removed, I’ll do my best to oblige. In other words, I’ll try to keep this blog up to date. The name against each 'smell' is the name of the person who Twittered me, commented about or who has written about the 'smell'. it does not imply that they were the first ever to think of the smell! Use of deprecated syntax such as *= (Dave Howard) Denormalisation that requires the shredding of the contents of columns. (Merrill Aldrich) Contrived interfaces Use of deprecated datatypes such as TEXT/NTEXT (Dave Howard) Datatype mis-matches in predicates that rely on implicit conversion.(Plamen Ratchev) Using Correlated subqueries instead of a join   (Dave_Levy/ Plamen Ratchev) The use of Hints in queries, especially NOLOCK (Dave Howard /Mike Reigler) Few or No comments. Use of functions in a WHERE clause. (Anil Das) Overuse of scalar UDFs (Dave Howard, Plamen Ratchev) Excessive ‘overloading’ of routines. The use of Exec xp_cmdShell (Merrill Aldrich) Excessive use of brackets. (Dave Levy) Lack of the use of a semicolon to terminate statements Use of non-SARGable functions on indexed columns in predicates (Plamen Ratchev) Duplicated code, or strikingly similar code. Misuse of SELECT * (Plamen Ratchev) Overuse of Cursors (Everyone. Special mention to Dave Levy & Adrian Hills) Overuse of CLR routines when not necessary (Sam Stange) Same column name in different tables with different datatypes. (Ian Stirk) Use of ‘broken’ functions such as ‘ISNUMERIC’ without additional checks. Excessive use of the WHILE loop (Merrill Aldrich) INSERT ... EXEC (Merrill Aldrich) The use of stored procedures where a view is sufficient (Merrill Aldrich) Not using two-part object names (Merrill Aldrich) Using INSERT INTO without specifying the columns and their order (Merrill Aldrich) Full outer joins even when they are not needed. (Plamen Ratchev) Huge stored procedures (hundreds/thousands of lines). Stored procedures that can produce different columns, or order of columns in their results, depending on the inputs. Code that is never used. Complex and nested conditionals WHILE (not done) loops without an error exit. Variable name same as the Datatype Vague identifiers. Storing complex data  or list in a character map, bitmap or XML field User procedures with sp_ prefix (Aaron Bertrand)Views that reference views that reference views that reference views (Aaron Bertrand) Inappropriate use of sql_variant (Neil Hambly) Errors with identity scope using SCOPE_IDENTITY @@IDENTITY or IDENT_CURRENT (Neil Hambly, Aaron Bertrand) Schemas that involve multiple dated copies of the same table instead of partitions (Matt Whitfield-Atlantis UK) Scalar UDFs that do data lookups (poor man's join) (Matt Whitfield-Atlantis UK) Code that allows SQL Injection (Mladen Prajdic) Tables without clustered indexes (Matt Whitfield-Atlantis UK) Use of "SELECT DISTINCT" to mask a join problem (Nick Harrison) Multiple stored procedures with nearly identical implementation. (Nick Harrison) Excessive column aliasing may point to a problem or it could be a mapping implementation. (Nick Harrison) Joining "too many" tables in a query. (Nick Harrison) Stored procedure returning more than one record set. (Nick Harrison) A NOT LIKE condition (Nick Harrison) excessive "OR" conditions. (Nick Harrison) User procedures with sp_ prefix (Aaron Bertrand) Views that reference views that reference views that reference views (Aaron Bertrand) sp_OACreate or anything related to it (Bill Fellows) Prefixing names with tbl_, vw_, fn_, and usp_ ('tibbling') (Jeremiah Peschka) Aliases that go a,b,c,d,e... (Dave Levy/Diane McNurlan) Overweight Queries (e.g. 4 inner joins, 8 left joins, 4 derived tables, 10 subqueries, 8 clustered GUIDs, 2 UDFs, 6 case statements = 1 query) (Robert L Davis) Order by 3,2 (Dave Levy) MultiStatement Table functions which are then filtered 'Sel * from Udf() where Udf.Col = Something' (Dave Ballantyne) running a SQL 2008 system in SQL 2000 compatibility mode(John Stafford)

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  • Customize Team Build 2010 – Part 13: Get control over the Build Output

    In the series the following parts have been published Part 1: Introduction Part 2: Add arguments and variables Part 3: Use more complex arguments Part 4: Create your own activity Part 5: Increase AssemblyVersion Part 6: Use custom type for an argument Part 7: How is the custom assembly found Part 8: Send information to the build log Part 9: Impersonate activities (run under other credentials) Part 10: Include Version Number in the Build Number Part 11: Speed up opening my build process template Part 12: How to debug my custom activities Part 13: Get control over the Build Output Part 14: Execute a PowerShell script Part 15: Fail a build based on the exit code of a console application     In the part 8, I have explained how you can add informational messages, warnings or errors to the build output. If you want to integrate with other lines of text to the build output, you need to do more. This post will show you how you can add extra steps, additional information and hyperlinks to the build output. Add an hyperlink to the end of the build output Lets start with a simple example of how you can adjust the build output. In this case we are going to add at the end of the build output an hyperlink where a user can click on to for example start the deployment to the test environment. In part 4 you can find information how you can create a custom activity To add information to the build output, you need the BuildDetail. This value is a variable in your xaml and is thus easily transferable to you custom activity. Besides the BuildDetail the user has also to specify the text and the url that has to be added to the end of the build output. The following code segment shows you how you can achieve this.     [BuildActivity(HostEnvironmentOption.All)]    public sealed class AddHyperlinkToBuildOutput : CodeActivity    {        [RequiredArgument]        public InArgument<IBuildDetail> BuildDetail { get; set; }         [RequiredArgument]        public InArgument<string> DisplayText { get; set; }         [RequiredArgument]        public InArgument<string> Url { get; set; }         protected override void Execute(CodeActivityContext context)        {            // Obtain the runtime value of the input arguments                        IBuildDetail buildDetail = context.GetValue(this.BuildDetail);            string displayText = context.GetValue(this.DisplayText);            string url = context.GetValue(this.Url);             // Add the hyperlink            buildDetail.Information.AddExternalLink(displayText, new Uri(url));            buildDetail.Information.Save();        }    } If you add this activity to somewhere in your build process template (within the scope Run on Agent), you will get the following build output Add an line of text to the build output The next challenge is to add this kind of output not only to the end of the build output but at the step that is currently executing. To be able to do this, you need the current node in the build output. The following code shows you how you can achieve this. First you need to get the current activity tracking, which you can get with the following line of code             IActivityTracking currentTracking = context.GetExtension<IBuildLoggingExtension>().GetActivityTracking(context); Then you can create a new node and set its type to Activity Tracking Node (so copy it from the current node) and do nice things with the node.             IBuildInformationNode childNode = currentTracking.Node.Children.CreateNode();            childNode.Type = currentTracking.Node.Type;            childNode.Fields.Add("DisplayText", "This text is displayed."); You can also add a build step to display progress             IBuildStep buildStep = childNode.Children.AddBuildStep("Custom Build Step", "This is my custom build step");            buildStep.FinishTime = DateTime.Now.AddSeconds(10);            buildStep.Status = BuildStepStatus.Succeeded; Or you can add an hyperlink to the node             childNode.Children.AddExternalLink("My link", new Uri(http://www.ewaldhofman.nl)); When you combine this together you get the following result in the build output     You can download the full solution at BuildProcess.zip. It will include the sources of every part and will continue to evolve.

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  • Customize Team Build 2010 – Part 13: Get control over the Build Output

    In the series the following parts have been published Part 1: Introduction Part 2: Add arguments and variables Part 3: Use more complex arguments Part 4: Create your own activity Part 5: Increase AssemblyVersion Part 6: Use custom type for an argument Part 7: How is the custom assembly found Part 8: Send information to the build log Part 9: Impersonate activities (run under other credentials) Part 10: Include Version Number in the Build Number Part 11: Speed up opening my build process template Part 12: How to debug my custom activities Part 13: Get control over the Build Output Part 14: Execute a PowerShell script Part 15: Fail a build based on the exit code of a console application In the part 8, I have explained how you can add informational messages, warnings or errors to the build output. If you want to integrate with other lines of text to the build output, you need to do more. This post will show you how you can add extra steps, additional information and hyperlinks to the build output. UPDATE 13-12-2010: Thanks to Jason Pricket, it is now also possible to not show every activity in the build log. This is really useful when you are doing for-loops in your template. To see how you can do that, check out Jason's blog: http://blogs.msdn.com/b/jpricket/archive/2010/12/09/tfs-2010-making-your-build-log-less-noisy.aspx Add an hyperlink to the end of the build output Lets start with a simple example of how you can adjust the build output. In this case we are going to add at the end of the build output an hyperlink where a user can click on to for example start the deployment to the test environment. In part 4 you can find information how you can create a custom activity To add information to the build output, you need the BuildDetail. This value is a variable in your xaml and is thus easily transferable to you custom activity. Besides the BuildDetail the user has also to specify the text and the url that has to be added to the end of the build output. The following code segment shows you how you can achieve this.     [BuildActivity(HostEnvironmentOption.All)]    public sealed class AddHyperlinkToBuildOutput : CodeActivity    {        [RequiredArgument]        public InArgument<IBuildDetail> BuildDetail { get; set; }         [RequiredArgument]        public InArgument<string> DisplayText { get; set; }         [RequiredArgument]        public InArgument<string> Url { get; set; }         protected override void Execute(CodeActivityContext context)        {            // Obtain the runtime value of the input arguments                        IBuildDetail buildDetail = context.GetValue(this.BuildDetail);            string displayText = context.GetValue(this.DisplayText);            string url = context.GetValue(this.Url);             // Add the hyperlink            buildDetail.Information.AddExternalLink(displayText, new Uri(url));            buildDetail.Information.Save();        }    } If you add this activity to somewhere in your build process template (within the scope Run on Agent), you will get the following build output Add an line of text to the build output The next challenge is to add this kind of output not only to the end of the build output but at the step that is currently executing. To be able to do this, you need the current node in the build output. The following code shows you how you can achieve this. First you need to get the current activity tracking, which you can get with the following line of code             IActivityTracking currentTracking = context.GetExtension<IBuildLoggingExtension>().GetActivityTracking(context); Then you can create a new node and set its type to Activity Tracking Node (so copy it from the current node) and do nice things with the node.             IBuildInformationNode childNode = currentTracking.Node.Children.CreateNode();            childNode.Type = currentTracking.Node.Type;            childNode.Fields.Add("DisplayText", "This text is displayed."); You can also add a build step to display progress             IBuildStep buildStep = childNode.Children.AddBuildStep("Custom Build Step", "This is my custom build step");            buildStep.FinishTime = DateTime.Now.AddSeconds(10);            buildStep.Status = BuildStepStatus.Succeeded; Or you can add an hyperlink to the node             childNode.Children.AddExternalLink("My link", new Uri(http://www.ewaldhofman.nl)); When you combine this together you get the following result in the build output   You can download the full solution at BuildProcess.zip. It will include the sources of every part and will continue to evolve.

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  • Web Site Performance and Assembly Versioning – Part 3 Versioning Combined Files Using Mercurial

    - by capgpilk
    Minification and Concatination of JavaScript and CSS Files Versioning Combined Files Using Subversion Versioning Combined Files Using Mercurial – this post I have worked on a project recently where there was a need to version the system (library dll, css and javascript files) by date and Mercurial revision number. This was in the format:- 0.12.524.407 {major}.{year}.{month}{date}.{mercurial revision} Each time there is an internal build using the CI server, it would label the files using this format. When it came time to do a major release, it became v1.{year}.{month}{date}.{mercurial revision}, with each public release having a major version increment. Also as a requirement, each assembly also had to have a new GUID on each build. So like in previous posts, we need to edit the csproj file, and add a couple of Default targets. 1: <?xml version="1.0" encoding="utf-8"?> 2: <Project ToolsVersion="4.0" DefaultTargets="Hg-Revision;AssemblyInfo;Build" 3: xmlns="http://schemas.microsoft.com/developer/msbuild/2003"> 4: <PropertyGroup> Right below the closing tag of the entire project we add our two targets, the first is to get the Mercurial revision number. We first need to import the tasks for MSBuild which can be downloaded from http://msbuildhg.codeplex.com/ 1: <Import Project="..\Tools\MSBuild.Mercurial\MSBuild.Mercurial.Tasks" />   1: <Target Name="Hg-Revision"> 2: <HgVersion LocalPath="$(MSBuildProjectDirectory)" Timeout="5000" 3: LibraryLocation="C:\TortoiseHg\"> 4: <Output TaskParameter="Revision" PropertyName="Revision" /> 5: </HgVersion> 6: <Message Text="Last revision from HG: $(Revision)" /> 7: </Target> With the main Mercurial files being located at c:\TortoiseHg To get a valid GUID we need to escape from the csproj markup and call some c# code which we put in a property group for later reference. 1: <PropertyGroup> 2: <GuidGenFunction> 3: <![CDATA[ 4: public static string ScriptMain() { 5: return System.Guid.NewGuid().ToString().ToUpper(); 6: } 7: ]]> 8: </GuidGenFunction> 9: </PropertyGroup> Now we add in our target for generating the GUID. 1: <Target Name="AssemblyInfo"> 2: <Script Language="C#" Code="$(GuidGenFunction)"> 3: <Output TaskParameter="ReturnValue" PropertyName="NewGuid" /> 4: </Script> 5: <Time Format="yy"> 6: <Output TaskParameter="FormattedTime" PropertyName="year" /> 7: </Time> 8: <Time Format="Mdd"> 9: <Output TaskParameter="FormattedTime" PropertyName="daymonth" /> 10: </Time> 11: <AssemblyInfo CodeLanguage="CS" OutputFile="Properties\AssemblyInfo.cs" 12: AssemblyTitle="name" AssemblyDescription="description" 13: AssemblyCompany="none" AssemblyProduct="product" 14: AssemblyCopyright="Copyright ©" 15: ComVisible="false" CLSCompliant="true" Guid="$(NewGuid)" 16: AssemblyVersion="$(Major).$(year).$(daymonth).$(Revision)" 17: AssemblyFileVersion="$(Major).$(year).$(daymonth).$(Revision)" /> 18: </Target> So this will give use an AssemblyInfo.cs file like this just prior to calling the Build task:- 1: using System; 2: using System.Reflection; 3: using System.Runtime.CompilerServices; 4: using System.Runtime.InteropServices; 5:  6: [assembly: AssemblyTitle("name")] 7: [assembly: AssemblyDescription("description")] 8: [assembly: AssemblyCompany("none")] 9: [assembly: AssemblyProduct("product")] 10: [assembly: AssemblyCopyright("Copyright ©")] 11: [assembly: ComVisible(false)] 12: [assembly: CLSCompliant(true)] 13: [assembly: Guid("9C2C130E-40EF-4A20-B7AC-A23BA4B5F2B7")] 14: [assembly: AssemblyVersion("0.12.524.407")] 15: [assembly: AssemblyFileVersion("0.12.524.407")] Therefore giving us the correct version for the assembly. This can be referenced within your project whether web or Windows based like this:- 1: public static string AppVersion() 2: { 3: return Assembly.GetExecutingAssembly().GetName().Version.ToString(); 4: } As mentioned in previous posts in this series, you can label css and javascript files using this version number and the GetAssemblyIdentity task from the main MSBuild task library build into the .Net framework. 1: <GetAssemblyIdentity AssemblyFiles="bin\TheAssemblyFile.dll"> 2: <Output TaskParameter="Assemblies" ItemName="MyAssemblyIdentities" /> 3: </GetAssemblyIdentity> Then use this to write out the files:- 1: <WriteLinestoFile 2: File="Client\site-style-%(MyAssemblyIdentities.Version).combined.min.css" 3: Lines="@(CSSLinesSite)" Overwrite="true" />

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  • Tricks and Optimizations for you Sitecore website

    - by amaniar
    When working with Sitecore there are some optimizations/configurations I usually repeat in order to make my app production ready. Following is a small list I have compiled from experience, Sitecore documentation, communicating with Sitecore Engineers etc. This is not supposed to be technically complete and might not be fit for all environments.   Simple configurations that can make a difference: 1) Configure Sitecore Caches. This is the most straight forward and sure way of increasing the performance of your website. Data and item cache sizes (/databases/database/ [id=web] ) should be configured as needed. You may start with a smaller number and tune them as needed. <cacheSizes hint="setting"> <data>300MB</data> <items>300MB</items> <paths>5MB</paths> <standardValues>5MB</standardValues> </cacheSizes> Tune the html, registry etc cache sizes for your website.   <cacheSizes> <sites> <website> <html>300MB</html> <registry>1MB</registry> <viewState>10MB</viewState> <xsl>5MB</xsl> </website> </sites> </cacheSizes> Tune the prefetch cache settings under the App_Config/Prefetch/ folder. Sample /App_Config/Prefetch/Web.Config: <configuration> <cacheSize>300MB</cacheSize> <!--preload items that use this template--> <template desc="mytemplate">{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}</template> <!--preload this item--> <item desc="myitem">{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX }</item> <!--preload children of this item--> <children desc="childitems">{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}</children> </configuration> Break your page into sublayouts so you may cache most of them. Read the caching configuration reference: http://sdn.sitecore.net/upload/sitecore6/sc62keywords/cache_configuration_reference_a4.pdf   2) Disable Analytics for the Shell Site <site name="shell" virtualFolder="/sitecore/shell" physicalFolder="/sitecore/shell" rootPath="/sitecore/content" startItem="/home" language="en" database="core" domain="sitecore" loginPage="/sitecore/login" content="master" contentStartItem="/Home" enableWorkflow="true" enableAnalytics="false" xmlControlPage="/sitecore/shell/default.aspx" browserTitle="Sitecore" htmlCacheSize="2MB" registryCacheSize="3MB" viewStateCacheSize="200KB" xslCacheSize="5MB" />   3) Increase the Check Interval for the MemoryMonitorHook so it doesn’t run every 5 seconds (default). <hook type="Sitecore.Diagnostics.MemoryMonitorHook, Sitecore.Kernel"> <param desc="Threshold">800MB</param> <param desc="Check interval">00:05:00</param> <param desc="Minimum time between log entries">00:01:00</param> <ClearCaches>false</ClearCaches> <GarbageCollect>false</GarbageCollect> <AdjustLoadFactor>false</AdjustLoadFactor> </hook>   4) Set Analytics.PeformLookup (Sitecore.Analytics.config) to false if your environment doesn’t have access to the internet or you don’t intend to use reverse DNS lookup. <setting name="Analytics.PerformLookup" value="false" />   5) Set the value of the “Media.MediaLinkPrefix” setting to “-/media”: <setting name="Media.MediaLinkPrefix" value="-/media" /> Add the following line to the customHandlers section: <customHandlers> <handler trigger="-/media/" handler="sitecore_media.ashx" /> <handler trigger="~/media/" handler="sitecore_media.ashx" /> <handler trigger="~/api/" handler="sitecore_api.ashx" /> <handler trigger="~/xaml/" handler="sitecore_xaml.ashx" /> <handler trigger="~/icon/" handler="sitecore_icon.ashx" /> <handler trigger="~/feed/" handler="sitecore_feed.ashx" /> </customHandlers> Link: http://squad.jpkeisala.com/2011/10/sitecore-media-library-performance-optimization-checklist/   6) Performance counters should be disabled in production if not being monitored <setting name="Counters.Enabled" value="false" />   7) Disable Item/Memory/Timing threshold warnings. Due to the nature of this component, it brings no value in production. <!--<processor type="Sitecore.Pipelines.HttpRequest.StartMeasurements, Sitecore.Kernel" />--> <!--<processor type="Sitecore.Pipelines.HttpRequest.StopMeasurements, Sitecore.Kernel"> <TimingThreshold desc="Milliseconds">1000</TimingThreshold> <ItemThreshold desc="Item count">1000</ItemThreshold> <MemoryThreshold desc="KB">10000</MemoryThreshold> </processor>—>   8) The ContentEditor.RenderCollapsedSections setting is a hidden setting in the web.config file, which by default is true. Setting it to false will improve client performance for authoring environments. <setting name="ContentEditor.RenderCollapsedSections" value="false" />   9) Add a machineKey section to your Web.Config file when using a web farm. Link: http://msdn.microsoft.com/en-us/library/ff649308.aspx   10) If you get errors in the log files similar to: WARN Could not create an instance of the counter 'XXX.XXX' (category: 'Sitecore.System') Exception: System.UnauthorizedAccessException Message: Access to the registry key 'Global' is denied. Make sure the ApplicationPool user is a member of the system “Performance Monitor Users” group on the server.   11) Disable WebDAV configurations on the CD Server if not being used. More: http://sitecoreblog.alexshyba.com/2011/04/disable-webdav-in-sitecore.html   12) Change Log4Net settings to only log Errors on content delivery environments to avoid unnecessary logging. <root> <priority value="ERROR" /> <appender-ref ref="LogFileAppender" /> </root>   13) Disable Analytics for any content item that doesn’t add value. For example a page that redirects to another page.   14) When using Web User Controls avoid registering them on the page the asp.net way: <%@ Register Src="~/layouts/UserControls/MyControl.ascx" TagName="MyControl" TagPrefix="uc2" %> Use Sublayout web control instead – This way Sitecore caching could be leveraged <sc:Sublayout ID="ID" Path="/layouts/UserControls/MyControl.ascx" Cacheable="true" runat="server" />   15) Avoid querying for all children recursively when all items are direct children. Sitecore.Context.Database.SelectItems("/sitecore/content/Home//*"); //Use: Sitecore.Context.Database.GetItem("/sitecore/content/Home");   16) On IIS — you enable static & dynamic content compression on CM and CD More: http://technet.microsoft.com/en-us/library/cc754668%28WS.10%29.aspx   17) Enable HTTP Keep-alive and content expiration in IIS.   18) Use GUID’s when accessing items and fields instead of names or paths. Its faster and wont break your code when things get moved or renamed. Context.Database.GetItem("{324DFD16-BD4F-4853-8FF1-D663F6422DFF}") Context.Item.Fields["{89D38A8F-394E-45B0-826B-1A826CF4046D}"]; //is better than Context.Database.GetItem("/Home/MyItem") Context.Item.Fields["FieldName"]   Hope this helps.

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  • C#/.NET Little Pitfalls: The Dangers of Casting Boxed Values

    - by James Michael Hare
    Starting a new series to parallel the Little Wonders series.  In this series, I will examine some of the small pitfalls that can occasionally trip up developers. Introduction: Of Casts and Conversions What happens when we try to assign from an int and a double and vice-versa? 1: double pi = 3.14; 2: int theAnswer = 42; 3:  4: // implicit widening conversion, compiles! 5: double doubleAnswer = theAnswer; 6:  7: // implicit narrowing conversion, compiler error! 8: int intPi = pi; As you can see from the comments above, a conversion from a value type where there is no potential data loss is can be done with an implicit conversion.  However, when converting from one value type to another may result in a loss of data, you must make the conversion explicit so the compiler knows you accept this risk.  That is why the conversion from double to int will not compile with an implicit conversion, we can make the conversion explicit by adding a cast: 1: // explicit narrowing conversion using a cast, compiler 2: // succeeds, but results may have data loss: 3: int intPi = (int)pi; So for value types, the conversions (implicit and explicit) both convert the original value to a new value of the given type.  With widening and narrowing references, however, this is not the case.  Converting reference types is a bit different from converting value types.  First of all when you perform a widening or narrowing you don’t really convert the instance of the object, you just convert the reference itself to the wider or narrower reference type, but both the original and new reference type both refer back to the same object. Secondly, widening and narrowing for reference types refers the going down and up the class hierarchy instead of referring to precision as in value types.  That is, a narrowing conversion for a reference type means you are going down the class hierarchy (for example from Shape to Square) whereas a widening conversion means you are going up the class hierarchy (from Square to Shape).  1: var square = new Square(); 2:  3: // implicitly convers because all squares are shapes 4: // (that is, all subclasses can be referenced by a superclass reference) 5: Shape myShape = square; 6:  7: // implicit conversion not possible, not all shapes are squares! 8: // (that is, not all superclasses can be referenced by a subclass reference) 9: Square mySquare = (Square) myShape; So we had to cast the Shape back to Square because at that point the compiler has no way of knowing until runtime whether the Shape in question is truly a Square.  But, because the compiler knows that it’s possible for a Shape to be a Square, it will compile.  However, if the object referenced by myShape is not truly a Square at runtime, you will get an invalid cast exception. Of course, there are other forms of conversions as well such as user-specified conversions and helper class conversions which are beyond the scope of this post.  The main thing we want to focus on is this seemingly innocuous casting method of widening and narrowing conversions that we come to depend on every day and, in some cases, can bite us if we don’t fully understand what is going on!  The Pitfall: Conversions on Boxed Value Types Can Fail What if you saw the following code and – knowing nothing else – you were asked if it was legal or not, what would you think: 1: // assuming x is defined above this and this 2: // assignment is syntactically legal. 3: x = 3.14; 4:  5: // convert 3.14 to int. 6: int truncated = (int)x; You may think that since x is obviously a double (can’t be a float) because 3.14 is a double literal, but this is inaccurate.  Our x could also be dynamic and this would work as well, or there could be user-defined conversions in play.  But there is another, even simpler option that can often bite us: what if x is object? 1: object x; 2:  3: x = 3.14; 4:  5: int truncated = (int) x; On the surface, this seems fine.  We have a double and we place it into an object which can be done implicitly through boxing (no cast) because all types inherit from object.  Then we cast it to int.  This theoretically should be possible because we know we can explicitly convert a double to an int through a conversion process which involves truncation. But here’s the pitfall: when casting an object to another type, we are casting a reference type, not a value type!  This means that it will attempt to see at runtime if the value boxed and referred to by x is of type int or derived from type int.  Since it obviously isn’t (it’s a double after all) we get an invalid cast exception! Now, you may say this looks awfully contrived, but in truth we can run into this a lot if we’re not careful.  Consider using an IDataReader to read from a database, and then attempting to select a result row of a particular column type: 1: using (var connection = new SqlConnection("some connection string")) 2: using (var command = new SqlCommand("select * from employee", connection)) 3: using (var reader = command.ExecuteReader()) 4: { 5: while (reader.Read()) 6: { 7: // if the salary is not an int32 in the SQL database, this is an error! 8: // doesn't matter if short, long, double, float, reader [] returns object! 9: total += (int) reader["annual_salary"]; 10: } 11: } Notice that since the reader indexer returns object, if we attempt to convert using a cast to a type, we have to make darn sure we use the true, actual type or this will fail!  If the SQL database column is a double, float, short, etc this will fail at runtime with an invalid cast exception because it attempts to convert the object reference! So, how do you get around this?  There are two ways, you could first cast the object to its actual type (double), and then do a narrowing cast to on the value to int.  Or you could use a helper class like Convert which analyzes the actual run-time type and will perform a conversion as long as the type implements IConvertible. 1: object x; 2:  3: x = 3.14; 4:  5: // if you want to cast, must cast out of object to double, then 6: // cast convert. 7: int truncated = (int)(double) x; 8:  9: // or you can call a helper class like Convert which examines runtime 10: // type of the value being converted 11: int anotherTruncated = Convert.ToInt32(x); Summary You should always be careful when performing a conversion cast from values boxed in object that you are actually casting to the true type (or a sub-type). Since casting from object is a widening of the reference, be careful that you either know the exact, explicit type you expect to be held in the object, or instead avoid the cast and use a helper class to perform a safe conversion to the type you desire. Technorati Tags: C#,.NET,Pitfalls,Little Pitfalls,BlackRabbitCoder

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